Abstract: Taking the non rockbased soil area from the inland hilly region in Zhejiang Province as study object, 998 permanent sample plots for Continuous Forest Inventory were used as modeling samples, the main site quality factors were screened out by the stepwise regression method by taking the annual biomass production per unit area as dependent variable, and integrated with direct assessment method. The quantitative site quality evaluation model was established based on the Quantitative TheoryⅠ. The site quality grade of each forestsite type was evaluated and the forest land area of each quality grade in the study area was calculated. The results showed that the altitude, slope position, aspect, soil depth and humus depth were the 5 leading factors for forest site quality evaluation. Taking biomass as site quality evaluation index was of important biological significance. The site quality evaluation model could be used to assess the site quality grade effectively, and it was of practical significance to be applied to forestry production.