An improved slip factor model based on Qiu model for centrifugal compressor was developed. A secondary flow term was added to the Qiu model to correct the slip factor. Furthermore

the difference between the exit blade angle and the maximum blade angle as well as the corresponding position was taken into account. The improved model was verified by CFD with subsonic impeller Krain4

transonic impeller Krain6 and IET200 impeller. The constant coefficient c of the secondary flow was discussed. Compared with the CFD results

there as small error of the improved model. Results showed that compared with Qiu model and other traditional slip factor model

the improved model had higher accuracy

and the average relative error was below 2%. This improved model is suitable for subsonic and transonic centrifugal compressors.