Soil erosin is a complex process and pervasive geomorphologic hazard (earth cancer) and its rate is counted as a comprehensive index for assessing degree of development and sustainability of land management programs of the countries. Due to the strong dependence of pedogenesis on geomorphic systems, there is a close relationship between geomorphic units and erosion at different spatial level. In this research the potential erosion rate of watershed was estimated by MPSIAC model within geomorphologic facies (as work unit) that differentiated on the homogeneity of topography. Litho logy and erosion reaction at semi-detailed level and 1:50000 scale. Based on obtained results, this watershed contains three from II to IV sediment yield and five from II to VI erosion intensity classes. Their mean specific sediment and erosion rates are 322 and 1105 m3/km2/y respectively. A regression equation with R=0.981 was established between specific erosion rate and effective factors of model in each geomorphic facies that significant at 5% level. Also, in multiple regression analysis (backward) all of the nine effective factors remained in the equation with R2=0.95478 at significant level. Differences of erosion rate inter geomorphologic unit(unit., type, sub-type and facies (76 polygons with repeat) and also differences in number and area of polygons of unit maps and sediment and erosion intensity map was compared by Chi-square test. In 17 tests, beside differences in polygon number of unit, sub-type, erosion and sediment maps, the other differences are significant at 0.01 to 0.05 (0.01