The sedimentary paleoenvironment of the Middle Permian Qixia Formation in northeastern Sichuan Basin was studied based on outcrop observations and laboratory analyses. The data correlations of the delta~(13)C and delta~(18)O of 19 samples from the Qixia Formation showed that there was no linear relationship between them. The samples are reliable targets for paleoenvironmental analyses since delta~(18)O>-6, Mn/Sr≤0.6, Fe/Sr<3, and MgO/CaO<0.125. The contents of terrigenous elements (Al_2O_3 and TiO_2) are low, and are strongly and positively correlated. The REE and (Al_2O_3+TiO_2) also showed a positive relationship. The characteristics of other main and trace elements indicated that the Qixia Formation was formed in a hypoxic or oxygen-depleted environment. The Sr/Ba value ranges from 21.9-261.9, indicating that the sea level was relatively high, so the terrigenous material content is low, and the terri-genous detrital sediments were controlled by paleo-water depth during sedimentation. The carbon and oxygen isotopes revealed that the ancient oceanic temperature ranged from 17.62-28.43 ℃, the paleosalinity ranged from 129.07-135.21, and the ratio of MgO/CaO ranged from 0.007-0.029, revealing that the paleoenvironmental climate was relatively warm and humid. Water depth fluctuated within a small range and experienced two transgressive and regressive cycles.