Forests located in the Zagros Mountains, as part of natural resources have different services. Soil retention is one of the most important services of forests. Population growth in recent decades has led to intensifying the exploitation of forests and uncontrolled destruction of them. Knowledge of ecosystem services as a new approach can help to prevent the destruction of forests. Current study was done by purpose of considering the role of forest ecosystems in soil retention as an ecosystem service and identification of areas with high supply of this service. InVEST software was used to model soil retention (SR), as the capacity of ecosystems to retain soil, by their equations. The results of the study showed that because of increasing the LS and R factors toward the south part of Lorestan province, the maximum potential of soil erosion was seen in the this region (1000 t/ha). The role of forests in soil retention was highlighted because spatial overlay of forest cover with maximum soil erosion areas was seen in the south part of Lorestan province. According to results the maximum of soil retention was allocated to forest cover compared to other land uses.