Abstract: A study on the site classification and its evaluation of poplar forest land in the plain formerly flooded by the Huanghe River has been conducted and data of 23 fixed sample plots for 4-6 years and other 56 plots in 4 counties in the plain formerly flooded by the Huanghe River were analyzed by means of quality and quantity determination. In the analysis, topography has not been used as the basis for classification, because the terrain slopes gradually and it has no influence on the growth of Populus tomentosa,while the stable soil type, its texture and its profile structure have been used as the main factors for site classification. They are graded according to the interrelationship between the soil characteristics and the growth of poplar. The site classification of the forest land in the plain formerly flooded by the Huanghe River is worked out according to the classified standards of the main factors. Based on the main site classifications, quality evaluation is made by means of the site index and soil characteristics.