Initially, Lan Hin Ngam was known by local villager. However, in 1985 (B.E. 2528), when Thep Sathit District Officer and Thep Sathit District Forest Officer surveyed and discovered of natural rock garden, which was very beautiful. They thought it should be conserved for tourism and recreation. Therefore, they presented document to the Royal Forest Department in order to set a national park. On the 10th October 1986 (B.E. 2529) this area was declared as Pa Hin Ngam Forest Park, with the area of 10km2.
In 1993 (B.E. 2536), the Royal Forest Department surveyed the area near by and found that 80km2 of surrounding forest is still fertilizing. Therefore, due to its fertile forest and fascinating features, this Forest Park was designated a national park on the 19th September 1994 (B.E. 2537).