The Guanling Biota occurs at the bottom of the Upper Triassic Xiaowa Formation, in Xinpu Town, Guanling County, Guizhou Province, China. Its fossils consist of marine reptiles (ichthyosaurus, thalattosaurus, sauropterygia and placodus), crinoid, ammonite, bivalve, brachiopod, condone, fish and plants. It is marked by a lot of marine reptiles and crinoid with features intact and delicate preservation. Two conclusions are made based on analysis of their lithofacies and paleogeography. One is that the animals of the Guanling Biota lived in a place at least 10 km away from the coastline in a bay concave to the northwest with weak current and low oxygen, and the other is that the emergence, development and extinction of the Guanling Biota are closely related to environmental evolution. The evolution of the Guanling Biota includes several stages: stable carbonate platform, a little far away from the coastline, the upper part of the Zhuganpo Formation deposited; a large-scale regression, resulting in the sharp lithological change between the Zhuganpo Formation and Xiaowa Formation; a near bay with frequent change of sea level, limestones with terrigenous material at the bottom of the Xiaowa Formation formed; a relatively stable bay not far from the coastline, the Guanling Biota prospered; violent environment, medium-bedded massive limestone with slumping structure formed, and the animals of the Guanling Biota run away.