The invention relates to a quantitative evaluation method for water and sand reduction effects of erosion and torrent control work. The quantitative evaluation method comprises the following steps: performing digital processing on a terrain; acquiring data of soil and water conservation measures; acquiring and processing other data; calculating water and sand; judging; transmitting variable parameters; performing model parameter calibration and model verification; setting soil and water conservation scenes; generating water and sand process data in different soil and water conservation scenes; analyzing and calculating soil and water conservation effects of the different soil and water conservation scenes; and comparing the effects, and completing the operation. According to the quantitative evaluation method, the data of the soil and water conservation measures of slope surfaces and other hydrological and meteorological data are collected, grid DEM (Dynamic Effect Model) data of different resolutions or contour strip data is adopted as a platform, real water and sand physical process of a hill is adopted as a view, the coupling simulation calculation ability of slope rainfall-runoff and erosion-sand process is achieved, soil and water conservation situations of the slope at different stages are compared and analyzed on premise that the water and sand process is precisely calculated, and thus the effects of the soil and water conservation measures can be very precisely acquired.