Abstract: The mid-deep formations of Yinggehai basin have enter into development stage. However, it is very necessary to do research on the "sweet spots" prediction because of the complex reservoirs. Firstly, the sensitive parameters of reservoir property are analyzed by rock physics analysis. According to theoretic rock physics, the reservoir porosity change can be studied through argillaceous rock content. Secondly, the seismic amplitude variation is simulated by the porosity change, which can realize the porosity quantitative prediction. The real seismic data application shows that the sands are developed at target stratum of X-district, and there are several "sweet spots" in this district. This paper can provide an effective support for "sweet spots" prediction and can be as a guidance for development well deployment at mid-deep formation of Yinggehai basin.