Duan Pidi (fl. 312–321) was a Duan-Xianbei chieftain during the Jin dynasty (266–420) and Sixteen Kingdoms period. He was the brother of chieftain Duan Jilujuan, and served as his general in the Jin's war with the Han-Zhao state. After Jilujuan made peace with Han in 313, Pidi led his branch of the tribe to continue fighting Han from Jicheng. Pidi became the most powerful Jin vassal in the north, but his decision to kill his ally, Liu Kun and a civil war with his cousin, Duan Mopei severely weakened him. In 319, he was forced to flee to another Jin vassal, Shao Xu. He was eventually captured by the Later Zhao in 321, and despite receiving favourable treatment from its ruler, Shi Le, he would later be executed in fear he would rebel.

Duan Pidi was a member of the Xianbei Duan clan of Liaoxi. His father, Duan Wuwuchen was the head of the clan between 303 and 311. At the start of the 4th century, the Duan clan allied with the Youzhou warlord, Wang Jun and played an important role in Wang's campaign against the Prince of Chengdu, Sima Ying, during the War of the Eight Princes. The Duan tribe and Wang Jun continued their association after the war, combining their efforts to stop the new and growing state of Han-Zhao. Some time around 310, Pidi's elder brother, Duan Jilujuan, succeeded Wuwuchen as chieftain following his death.

Duan Pidi participated during Jilujuan's attack on Xiangguo in 312, as part of Wang Jun's plan to divert the Han general, Shi Le, away from the rebelling city of Yuanxiang (苑鄕, in present-day Hebei and Beijing). The Duan forces fought Shi Le at Xiangguo but their star general, Pidi's cousin, Duan Mopei, was captured in battle. Despite being a prisoner, Mopei was treated with courtesy by Shi Le, which pleased Jilujuan. Because of this, the Duan tribe ceased their enmity with Shi Le and distanced themselves from Wang Jun.

Wang Jun was captured and executed by Shi Le in 314. After Wang's defeat, Shi Le appointed a man named Liu Han (劉翰) to be acting Inspector of Youzhou based in Jicheng. However, Liu Han instead fled to Duan Pidi, who he offered control over Jicheng. Pidi accepted on his own accord before occupying the city and submitting himself to Sima Rui, the paramount leader of the Jin in the south. For this, Sima Rui made Pidi Jin's new Inspector of Youzhou. Pidi also urged Shi Le's Administrator of Leling, Shao Xu, to submit to the Jin prince as well. Shao Xu did so, and Shi Le immediately responded by sending his army to besiege him. However, Pidi sent Duan Wenyang to reinforce Shao Xu, so Shi Le called off his attack.

In 316, Shi Le sent his nephew Shi Hu to attack the Administrator of Wei Commandery, Liu Yan (劉演). Pidi sent Wenyang to rescue Liu Yan, and while the commandery fell, Liu Yan was safely retrieved. Later that year, the Inspector of Bingzhou, Liu Kun lost his province to Shi Le. Liu Kun was left with nowhere to go, so Pidi sent a letter to invite him to his base. Liu Kun took what was left of his army to meet with Pidi and the two men quickly became friends. Forming a brotherly bond, Pidi and Liu Kun arranged their relatives to marry one another to further cement their friendship.

The next year, Pidi and Liu Kun swore an oath of alliance by smearing their lips with blood. Afterwards, they sent their respective envoys to deliver a joint petition urging Sima Rui to claim the imperial title. Liu Kun chose his nephew Wen Jiao to deliver the petition, while Pidi chose his Chief Clerk of the Left, Rong Shao (榮卲). After their envoys reached the southern capital, Pidi proclaimed Liu Kun as Grand Commander. He also later tried to get Jilujuan to join forces with him in a campaign against Shi Le. However, Duan Mopei advised Jilujuan against agreeing with Pidi, so Jilujuan did not respond, and Pidi had to cancel the campaign.

Jilujuan died in early 318 and was succeeded by his uncle, Duan Shefuchen. Pidi left Jicheng to attend his funeral but without his knowledge, Duan Mopei manipulated Shefuchen into believing that Pidi was about to usurp his power. At Zuobeiping, Shefuchen attacked Pidi but was betrayed by Mopei who assassinated him while his and Pidi's forces were fighting. Mopei then took command of the assault and routed Pidi. During this, Mopei capturing Liu Kun's son Liu Qun (劉群), who was escorting Pidi to the funeral.

Mopei treated Liu Qun well and considered supporting Liu Kun into becoming the new Inspector of Youzhou. He had Liu Qun write a letter to his father asking him to work as an agent within Pidi's camp, but his envoy was caught by Pidi's scouts along the way. Liu Kun knew nothing of the letter when Pidi confronted him with it. Pidi did not suspect Liu Kun, and Liu Kun himself assured him that he had no intentions to betray Pidi. Pidi let him off at first, but his younger brother, Duan Shujun (段叔軍), was able to get his brother to reconsider his actions.