Thung Salaeng Luang National Park is a national park located in the Phitsanulok and Phetchabun Provinces of Thailand. It encompasses substantial portions of Amphoe Wang Thong and Amphoe Lom Sak.
The park consists of limestone hills, slate and hardpan at altitudes ranging from 300 to 1,028 meters. Thung Salaeng Luang is inlaid with meadows, especially in the southern portions of the park. The park is also the source of numerous streams. There are large salt licks at Pong Sai in the north-west and Pong Thung Phaya in the south-west. the Wang Thong River flows through the park.
The park's forest is primarily classified as deciduous, with lowland scrub and tropical broadleaved evergreen covering smaller areas.