Phu Chi Fa (Thai: ภูชี้ฟ้า, pronounced [pʰūː t͡ɕʰíː fáː]), also Phu Chee Fah, is a mountain area and national forest park in Thailand. It is located at the northeastern end of the Phi Pan Nam Range, 12 km to the southwest of Doi Pha Tang at the eastern edge of Tap Tao in Thoeng district, Chiang Rai province.

The cliff is part of an elevated area, the Doi Pha Mon sub-range, that rises near the border with Laos sloping towards the Mekong River which has an area of approximately 58,069 rai ~ 92.91 km² (35.87 sq mi). The heights range between 1,200 and 1,628 m (3937 and 5341 ft) to the east of the mountain.

With views over the surrounding mountains, it is one of the famous tourist attractions of the Thai highlands near Chiang Rai. Tourists visit the mountain especially at dawn to catch a glimpse of the "sea of mist" and the view of the fog-surrounded hills.

Phu Chi Fa is part of the Doi Pha Mon mountain range, which is the border between Thailand and Laos in Chiang Rai–Phayao provinces. It has a steep cliff, so it was named "Phu Chi Fa." It is believed that Phu Chi Fa was once home to ancient tribes, such as the Akha or Hmong people. Locals call the ridge pointing to the sky "Chi Fa".

In the years between 1965 and 1983, this area was a battlefield due to ideological conflicts between groups that adhered to communist principles, who formed the Communist Party of Thailand, and government officials who were sent to suppress them, resulting in tragic and bloody confrontations. After the security problems were resolved, a road was built along the Thai–Laos border from Ban Pha Tang, through Phu Chi Fa, and to Chiang Kham district. Since then, Phu Chi Fa has been well known to tourists since 1991, and The Forest Department ordered it to be a forest park again on February 6, 1998.

Phu Chi Fa is home to various animals. From the survey and interviews with local residents, the wildlife in the surveyed national forest reserve can be broadly categorized as follows:

The forest around Phu Chi Fa supports a wide variety of plant species, contributing to the region's rich biodiversity. Tree species include the white orchid tree (Bauhinia variegata), sweet chestnut (Castanea sativa), Fagus hayatae, red beech (Fagus grandifolia), water beech (Fagus sylvatica), and giant beech (Fagus japonica). Other prominent trees include Terminalia bellerica, known for its use in traditional medicine, cinnamon (Cinnamomum verum), and aromatic species like frankincense (Boswellia sacra) and jambolan (Syzygium cumini). Wild flowering trees, such as Michelia alba, sarapee (Magnolia sirindhorniae), wild champak (Magnolia champaca), and wild magnolia, add seasonal blooms to the forest canopy.

The forest understory is equally diverse, supporting plant species such as ground orchids, cogon grass (Imperata cylindrica), vetiver grass (Chrysopogon zizanioides), rat-tail grass (Sporobolus indicus), and broom grass (Thysanolaena maxima). Mosses and various fern species thrive in the moist, shaded conditions, creating a lush, layered landscape beneath the taller trees. This combination of towering trees and a rich understory provides an intricate ecosystem, sustaining a wide array of wildlife and enhancing the natural beauty of the region.