Abstract: In this paper,an investigation was made on the Toona sinensis plantation in Suining region,and analysis was made of the relationship between average height of dominant trees and site conditions (soil texture, underground water level, drainage, interbed ded stratum, pH value soil parent materials, compaction, etc) in different sample plots. Finally a quantitative site index table was drawn up,including the four factors of the soil texture, ground water level, drainage condition and double-layered stratum. This table would be a good guidance for afforestation and forest management of Toona sinensis in this area.