Zhajiangmian (Chinese: 炸醬麵; pinyin: zhájiàngmiàn), commonly translated as "noodles served with fried bean sauce", is a dish of Chinese origin consisting of thick wheat noodles topped with zhajiang, a fermented soybean-based sauce. Variations may include toppings of fresh or pickled vegetables, beans, meat, tofu, or egg.

Zhajiangmian originated in Shandong, China and is a popular dish that has evolved into distinct versions across many cuisines both within and beyond China. The most well-known variation is arguably Beijing zhajiangmian (北京炸醬麵), which is recognized as one of the Ten Great Noodles of China (中國十大麵條). Zhajiangmian has also been adapted into the cuisines of South Korea (as jajangmyeon), and Japan (as jajamen).

The origin of zhajiangmian is widely attributed to northern China and sometimes specifically accredited to the coastal province of Shandong.

There are several theories of zhajiangmian's origins, many of which revolve around Chinese monarchs. The veracity of these claims is tenuous as important inventions in Chinese history were frequently attributed to prominent leaders and figures of the time. One theory maintains that the earliest form of zhajiangmian was created during the late 16th century in Manchuria by Nurhaci, the Emperor Taizu of Qing. Sources claim that during the Jurchen unification, Nurhaci commanded his troops to "supplant rations with jiang" (以醬代菜) by dissolving solid slabs of fermented soybean (醬坯) in water, creating a protein- and sodium-rich paste, and consuming it as a dip with vegetables.

Another theory suggests that zhajiangmian was discovered in Xi'an, Shaanxi and introduced to Beijing by the Empress Dowager Cixi. In 1900, forces of the Eight-Nation Alliance invaded Beijing. The entire imperial court, including Empress Dowager Cixi and the Guangxu Emperor, fled Beijing and evacuated to Xi'an. The empress's retinues were wearied by the time they reached Nan Dajie [zh] (南大街) in Xi'an, where the imperial Grand Supervisor (大總管), Li Lianying, discovered a noodle restaurant by its appetizing aroma. The empress dowager and emperor dined at the restaurant, each partaking of a bowl of vegetarian zhajiangmian. Cixi was so impressed by the dish that on their return to Beijing, she ordered that the noodle chef join her court.

Analysis of the subjective factors such as Beijing city development in Qing and Ming dynasties, food supply, climate, people's living conditions comes to a conclusion that Bean Paste Noodles and Old Beijing Noodles with Fried Bean Sauce occurred at the same time. The symbolic sign "Old Beijing Noodles with Fried Bean Sauce" is hidden but rich in profound cultural connotation.

In Shandong cuisine, the sauce is made with tianmianjiang and this version of zhajiangmian is commonly viewed as the standard within China.

In Beijing cuisine, yellow soybean paste and tianmianjiang are combined to make the sauce. During the process of frying the sauce, a large amount of white scallion is added, and diced pork is used instead of ground meat. Typically the dish is served with a variety of crunchy vegetables, such as cucumber, radish, roseheart radish, bean sprouts, celery, and soybeans. Thick handmade noodles are preferred. In China, Beijing-style zhajiangmian is the most well-known version, even over the original Shandong zhajiangmian.^{[citation needed]}