Sop Moei (Thai: สบเมย, pronounced [sòp mɤ̄ːj]) is the southernmost district (amphoe) of Mae Hong Son province, northern Thailand.

Tambons Sop Moei, Mae Khatuan, and Kong Koi were separated from Mae Sariang district to create Sop Moei minor district (king amphoe) on 1 April 1984.

The Thai government, to solve persistent water shortages in the central region, have proposed a 70.7 billion baht plan to divert some 1.8 billion m3 of water annually from the Yuam River to the perennially-underfilled Bhumibol Dam.

As part of the plan, the Royal Irrigation Department (RID), would build 69 metre high dam with a storage capacity of 68.7 million m3 constructed on 2,075 rai of forest land, together with a pumping station on a separate 55 rai plot and a 61.5 kilometre-long tunnel passing through 14 villages.

ONEP rejected the EIA for the second time due to concerns about forest destruction, tunnel rock waste, and compensation issues.