With increasing concentrations of greenhouse gases and global warming, climate change is one of the key topics of environmental science and engineering has become. Global warming will lead to changes in the hydrological cycle, including change in total amount of rainfall and intensity of extreme precipitation events. In effect change in the future due to climate change, expected change rate and volume erosion there are various ways. The most direct impact of climate change on soil erosion refers to the increasing power of rainfall erosivity factor. The main objective of this study is to determine the climate change impacts on rainfall erosivity factorin Haraz-Gharehsou Mazandaran province. One of the main parameters in the equation rain erosion index Universal Soil erosion (USLE) is the best method to estimate this index, the method Whichmeier is (R = (EI30) / 100). In this study, using statistics rain gauge stability in the stations studied (Babolsar , Noshahr and Gorgan) 30-year period in order to coordinate the different studies of climate change in the base period and to compare them 30-year period in order to coordinate the different studies of climate change in the base period and to compare them.The kinetic energy of rain was rain and finally R, and the sum of R rains every year, Ryear, respectively.Now for simulation R for future periods using meteorological parameters First of climate model outputs HadCM3 under the emission scenarios A2, B2 and B1 was used. Downscaled meteorological parameters of SDSM and LARS-WG was performed using models. And meteorological parameters for the periods (2030-2011), (2046-2065) and (2099-2080), was simulated by models expressed. Then, create a regression equation between annual precipitation data and index values R at each station based on the first data base (observation data) CalculationAnd then the relationship between annual precipitation and erosion of the stations (Babolsar, Noshahr and Gorgan) were calculated using software. The most appropriate relationship between annual precipitation stations and erosion of universal equation of soil erosion due to the higher coefficient of determination Evaluation and statistics were lower. Then, with the purpose of monitoring changes in the studied area of erosion, erosion factor for future periods (2030-2011), (2046-2065) and (2099-2080) was simulated.The simulation results showed that rainfall erosivity factor in Babolsar stations, Noshahr and Gorgan in the coming period will be reduced. The results showed that the average annual rainfall stations, Babolsar, Branch Gorgan approximately 884, and 615 mm is 1262/30. Since the R in rainy regions more than 1000 (Mj.mm/ha/hr/yr) and in the arid region less than 1000 (Mj.mm/ha/hr/yr) is the average R respectively 1079/25, 1284/35 and 80/835 (Mj.mm/ha/hr/yr), respectively. Key Words: Climate change, Downscaling, rainfall erosivity, SDSM, LARS-WG, Hadcm3.