Abstract: In mountainous and hilly regions, converting cultivated land into forests is an important measure to prevent degeneration of the ecological environment. Taking current cultivated land in Jinan as an example, this paper introduced the ecological niche concept to evaluate cultivated land fitness. According to the matching relations between current ecological niche and demanding ecological niche, seven main indexes were chosen including topographical factors, soil condition, ecological factors and irrigation condition and so on to set up an ecological niche fitness evaluation model of cultivated land. Attribute data was combined well with spatial data to calculate ecological niche fitness of each unit by GIS technology, and then the plots, which need to be converted into forests were defined. Results show that over 80% of the current cultivated land is in good quality in Jinan city, and 6.88% of the current cultivated land is not suitable and should be converted into forests step by step.