Software quality measurement is closely connected with process and product. With measurement and analysis on software process data, improvement and control on software can be achieved. Effective process performance model plays key role in understanding and controlling. Introduction of GQM model into software measurement process can achieve controllability and testability of software process. GQM uses organization target as measurement index to achieve measurement of software process quantitative. The core idea of CMM/CMMI is to build fact-based management and CMM/CMMI software process management is built on the basis of software measurement. Combining with CMM/CMMI measurement idea, GQM model was expanded to achieve a kind of improved process performance model.