Satellite precipitation products have been used in scientific studies in global and regional scales from several decades ago. The purpose of this research is quantitative comparison between TRMM and GPM precipitation products in Kashafrud basin. The important point about these products is their accuracy and pixel size. GPM satellite launched on 28th February 2014 and there is no research in Iran and few in the world. This research aims to assess GPM and its predecessor i.e. TRMM products in comparison with 34 ground rain gauge stations in the basin. Comparisons are done in basin and gauge spatial scales and each in daily and monthly time scales. For validation, the statistical metrics including RMSE, MAE, CC, BIAS, FAR, POD and CSI are used. The results indicated that generally the 3B42V7 product from TRMM has higher accuracy than IMERG product from GPM in our study region. IMERG product only in monthly and basin scale has better accuracy in comparison to 3B42V7 product. Regarding time scale comparison, monthly analysis showed higher accuracy. RMSE value for TMPA product in daily time scale for rain gauge and basin scale is 1.88 and 1.55 and in monthly scales is 2.87 and 2.77, respectively. Also, RMSE for IMERG product in rain gauge and basin in daily time scale is 2.43 and 2.3 and for monthly time scale 3.64 and 2.56, respectively.