Abstract: A new method to optimize and select common master images based on the minimum sum of three baselines is presented and implemented,which further integrates and optimizes three main parameters of impacting the correlation of interferograms on the basis of the existing models.A contract experiment about optimal selection of common master images in PS InSAR is carried out with 19 ERS-1/2 SLC SAR images and 10 ENVISAT ASAR images.Theoretical analysis and the experimental results show that,compared with the existing method,the new method to optimize and select common master images is simple and practical,and the selected common master images are more reasonable and accurate.