Seismic inversion includes pre-stack inversion and post-stack inversion. There are some limitations when used alone, because both methods have different scope. It is hard to describe the reservoir in Yong3 area because of the complex geological condition.In order to solve this problem, the joint inversion is proposed based on a series analysis of rock physics, model, algorithm and interpretation. According to the advantage of each method in reservoir and fluid description, the unified model and algorithm are used to control the relevance, as well as improving the consistency and comparability of both results. The joint inversion of pre-stack and post-stack achieves a detailed description of the reservoir and fluid characteristics in Yong3 area with the prediction accuracy rate over 80% of Es2 layer.