The fungi are an important component to the biomass of the forest soil and microbial flora. Through scene sampling, indoor culturing, observing, and exterminating, soil fungi quantity's ecology distribution and fungi class group of three kinds of different age of Jatropha curcas L. forests in Yongsheng County is comparatively analyzed with the related soil nutrient's relations. The result indicates that the soil fungi quantity variance between the different age of forests is remarkable, appearing as the quantity in the years of 21 to 30 > in the years of 11 to 20 > in the years of 1 to 10. Soil fungi has a significant variance of vertical distribution, appearing as the most in the depth range of 10—15cm, and the least in the depth range of 25—30cm. The fact indicates that in the soil depth of 10—15cm, root distribution is densified, root exudation is massive, porosity is high, moisture is adequate, and it provides abundant nutrition and appropriate living conditions. Saccharomyces (Meyer) Reess is the dominant genus among the 20 genera of fungi isolated from soil in the three kinds of different growing stages of Jatropha curcas L. forests; it plays an important role in the microecological balance formation of the Jatropha curcas L., and they are the superior fungal flora. Through comprehensive comparison and analysis on the fungal diversity index, it is found that the Shannon-Wiener diversity index and evenness index of fungal flora isolated from the Jatropha curcas L.forest with the ages of 11 years to 20 years is higher than that from 1 year to 10 years and 21 years to 30 years, the fact might be closely related to soil fertility and forest health.