Using quantitative methods, the evolution process of formations, geothermal field, hydrocarbon generation and drainage, diagenesis, porosity, accumulation times, traps and the driving force window are simulated, and the space-time matching of key accumulation factors are further analyzed. The results show that beginning form the Early Cretaceous, the regional structural subsidence and incidental significant geothermal event triggered the generation and drainage of source rocks. Dissolution of organic acid before accumulation period dramatically improved the porosity of Chang 8 reservoir which provides enough space for oil accumulation.