Abstract: Methods for GPS data processing with carrier phase observations are dealt with in this paper.There are some relationships existing among these processing methods.The equivalent conditions for eliminating nuisance parameters are further extended to fit centralized undifferential method as well as various differential methods.Based on these conditions,the equivalence is proved among original undifferential method,differential method centralized undifferential method and Goad undifferential method.Finally,after a review of GPS data processing method,some conclusions are made and they should be useful to various GPS applications for selecting suitable method in data processing.