Platysternon megacephalum hails from Southeast Asia. Specimens have been obtained as far south and west as Burma, and as far north and east as southern China. The most colorful subspecies, P. m. shiui , is located in northern Vietnam. In all of these locales, the primary habitat of the Big-headed turtle remains the same. It prefers to live in fast-moving mountain streams filled with boulders and broken rock.
Turtles spend the day underwater, burrowed into gravel deposits or hidden in crevices in the rocks.
In the evening they emerge to search for food along the stream bottom and out of water along the sides of the stream. The rapid water flow in the streams they frequent makes the ability to cling to rocks more advantageous than skill in swimming. The climbing ability of the Big-headed turtle should not be underestimated. The bridge between their carapace and plastron is somewhat reduced, allowing the turtle a large range of motion with its feet. The heavy head of P. megacephalum places the turtle's center of gravity well forward compared to other turtles.