Si Satchanalai (Thai: ศรีสัชนาลัย, pronounced [sǐː sàt.t͡ɕʰā.nāː.lāj]) is the northernmost district (amphoe) of Sukhothai province, in the lower northern region of Thailand.

The Phi Pan Nam Mountains dominate the landscape of the district.

Si Satchanalai was the second-most important town of the Sukhothai Kingdom.

[3] The district is divided into 11 sub-districts (tambons), which are further subdivided into 148 villages (mubans).

Hat Siao covers parts of tambon Hat Siao, and Si Satchanalai covers tambons Si Satchanalai, Tha Chai, and parts of Nong O.