Based on the GC-MS, the variation of organic matter origin, deposition environment and thermal maturity of hydrocarbon source rocks were systematically discussed. The distribution of tricyclic terpane is normal distribution with the main peak of C₂₃, high content C₂₄ tetracyclic terpane and a predominance of C₂₇ααα20R sterane over C₂₉ααα20R sterane with asymmetry "V" distribution indicates that the organic material of source rocks are higher terrigenous plants mixed with lower aquatic organisms. The main peak of hopanes is C₃₀ hopane with the distribution of C₃₁-C₃₅ hopane decline as a ladder and the tricyclic terpane/hopane ratio is high shows the lacustrine facies characteristics. The Pr/Ph value (0.44~0.49) and gammacerane/C₃₀ hopane value (0.32~0.38) indicate that source rocks are developed in brackish water reductive semideep-deep lake environment. The maturity parameters of C₂₉ααα20S/(20S+20R), C₂₉αββ/(ααα+αββ) and C₃₁αβ22S/(22S+22R) have reached the balanced endpoint value of isomerization, indicating the source rocks stay in mature-high mature stage during the thermal evolution.