[Objective] The land use benefits from grain-for-green project in Mudanjiang City were evaluated, and we expected to propose some scientific bases for rational land exploitation and structural adjustment of land use.[Methods] Based GIS spatial analysis, six natural indicators, including slope gradient, elevation, soil type, coefficient of water resource, precipitation, and ≥10℃ accumulated temperature were calculated. They were used as evaluation factors to assess the suitability of lands in Mudangjiang City for cultivated land and forestry land.[Results] The results showed that the land area assessed suitable to cultivation was about 9300 km², accounting for 22.9% of the study area. The slope gradient of these lands is below 5ånd the elevation is below 500 m. Lands assessed with forestry suitability grade had about 28000 km², covered 69.0% of the study area and mainly located at mountainous region, where both the elevation and slope gradient are great and the soil is vulnerable and erosive.[Conclusion] In forest-agriculture zone, present land use exists a phenomenon of overly returning farming land to forestry. This might cause the waste of suitable cultivation lands.