Gully erosion is one of the types of ever-intensified water erosion whose occurrence and spread makes noticeable changes in terms of land degradation and environmental destruction. Considering the diversity and extent of the effect of various factors on the formation and expansion of gully erosion, which change from one point to another in terms of type and extent of effects, and in order to identify the most important factors contributing to the development of gully erosion on the lands, in this research, IRS satellite imagery of India, field inspection and vast field operations through GPS were used and the map of gully erosion distribution was prepared In order to identify, by aerial photographs to a scale of 1:20,000, the ways of preventing and controlling this type of erosion in the basin of Rahjerd, which is a watershed located in the province of Qom. Studies showed that lithology characteristics, slope, resources and land suitability, direction of slope and land use are the main factors affecting the occurrence of gully erosion. The results of this study showed that the lithological units of 25.88 per cent Mpa.bvt and 74.12 per cent QFt2 and the land type of fan debris flow in the form of gravel (alluvial fan) have affected 100% of the areas struck by gully erosion. In addition, the slope of 0-10% (93.6%), eastward slope (63.09%), and medium range pastures use (100%) have the most expanses of areas affected by gully erosion in the studied basin area.