Ciying Formation in L Basin,which has the shallow layer,is characterized by shallow bury and complex geological origin.As the reservoir in Ciying Formation has high porosity and moderate permeability or high porosity and low permeability,it is a typical unconsolidated sandstone reservoir.With its rapid lateral variation and strong anisotropism,it's very difficult for elastic impedance and AVO techniques to make further distinction.In view of such a situation,the authors took advantage of prestack simultaneous inversion to make a prediction of shallow unconsolidated sandstone reservoirs.Based on seismic data,logging information and rock physics information,the authors applied prestack simultaneous inversion to finally get several elastic parameters such as P-impedence,S-imedence,and density.With these attribute parameters,the reservoirs can be easily and effectively predicted.