Topographical and pedological factors at 9 sites of Tuber indicum in Yunnan, Sichuan and Tibet were studied by using principal component analysis in order to determine the connection between truffle-growth with topographic factors and soil factors. Results showed that: 1) The 5 principal components selected from 15 topographical and pedological factors had a great cumulative contribution, up to 87.5%. Among the topographical factors, the slope position was the most important ecological factor affecting truffles growth. The higher the slope position was, the less conducive to truffles growth. In the middle and lower parts of the slope, T. indicum grew best. 2) As for the pedological factors, the bulk density, silt content, pH, total nitrogen content, exchangeable calcium and magnesium contents were the important factors restricting T. indicum growth. Under the condition of bulk density 0.65-0.82 g · cm(-3), silt content 30.0% and sand content about 55.0%, T. indicum grew well. Too high bulk density or clay content was not conducive to its growth. The soil with pH 6.40 or so, total nitrogen content of 2.29-3.70 g · kg(-1), exchangeable calcium content of 22.91-37.17 cmol · kg(-1) and exchangeable magnesium content of 1.85-2.59 cmol · kg(-1) were favorable for growth of T. indicum. 3) The comprehensive evaluation showed that the site at Shaoshang Village in Kunming, Yunnan and Jiangsegang Village in Linzhi Prefecture, Tibet had higher scores, which meant these two sites had the most favorable conditions for truffles growth. However, the site at Ershijiu-liangzi Village in Panzhihua, Sichuan and the Mt. Wuding in Chuxiong Prefecture, Yunnan had lower scores, which meant these two sites were not fit for truffles growth regarding the topographical and soil conditions.