Abstract: In this paper, researches were conducted on influence factors of Larix principis-rupprechtii disease index, and their correlation and regression reiationship with stand and sites. The results showed that the disease index and the density of Larix principis-rupprechtii displayed an extremely significant positive correlation, and yet the disease index had a significantly negative correlation with diameter at breast height and diversity index. Regression analysis showed that the influence of the density on the disease index was the greatest.