Abstract: Well pattern infilling is one of the main techniques in the development of tight sandstone gas reservoir,which can increase the sweep area,increase the production degree of reserves and enhance the recovery of gas wells.Shaximiao formation gas reservoir in Xinchang gas field is a typical tight sandstone gas reservoir.Through the analysis of its geological characteristics and gas well performance,comprehensive engineering technology,economic evaluation and numerical simulation,the encryption optimization of well pattern and well spacing in Shaximiao formation gas reservoir is carried out,and the reasonable well spacing of single layer,the encryption potential of gas field and the relationship between well pattern density and economic benefits are determined.Combined with the effect analysis of infilling wells,the development mode of multiple layers combined production by "better with worse" is put forward,which realizes the infilling mode of well pattern combining the maximization of well controlled reserves and recovery,and the optimization of economic benefits.After being applied to CX633 well group,a good development effect and economic benefit have been obtained,which can provide strong technical support for efficient development of gas reservoir.