Namtok Huai Yang National Park (Thai: อุทยานแห่งชาติน้ำตกห้วยยาง, RTGS: Utthayan Haeng Chat Namtok Huai Yang, pronounced [ʔùt.tʰā.jāːn hɛ̀ŋ tɕʰâːt nám.tòk hûaj jāːŋ]) is a national park in Thailand, consisting of several waterfalls and forests on the mountain range bordering Thailand and Myanmar.

The adjacent protected area is Lenya National Park of Myanmar.

[3] Namtok Huai Yang National Park covers an area of 100,625 rai ~ 161 square kilometres (62 sq mi)[4] of Thap Sakae and Bang Saphan Districts, Prachuap Khiri Khan Province, western Thailand.

Travel by car, the main route is Phet Kasem Road (Highway 4), about 36 km (22 mi) from the Prachuap Khiri Khan town, and 145 km (90 mi) from Hua Hin town.

[2] [5] The species of wildlife that can be found here are Indochinese leopard, mainland serow, wild boar, Indian muntjac, Malayan porcupine, include a variety of leaf monkeys and gibbons.