Screw pump performance test system consists of hardware system and software system. According to the hardware setup and testing principle, an integral software system was designed to detect screw pump performance parameter based on VB60 and dynamic link library. The designed software included basic parameter setting module, realtime data acquisition module, data processing and curve plotting module and data storage and report generation module. Because the testing conditions were limited and performance data acquired may not be expected, the analysis and processing of test data were the core of software system. The test data were analyzed by polynomial fitting based on least square method. And the polynomial fitting equation gained was used to predict the performance data of nontest points to improve the efficiency for screw pump testing. To increase the generality and portability of polynomial fitting procedure, it was encapsulated in standard DLL file based on VC++60 platform. The result states that the system can achieve functional requirements of screw pump performance testing and fulfills the analysis and processing of test data quickly and accurately.