Soil C, N, P and its stoichiometric ratio are important indexes to measure energy of ecosystem, multi-element equilibrium and the composition of soil organic matter. When alien plants invade, they usually change local soil environment and create an appropriate growth environment by withered fallen and scattered matters or allelopathic substances, and create an appropriate growing environment, they usually inhibit the other plants to grow and develop. In this paper, the soil of the Conyza canadensis invaded communities in different degrees in Yili River Valley is selected to study the change characteristics of carbon, nitrogen and phosphorus content, ecological chemometrics and its changing rules. As a result, the content of C, N and P in soil was significantly increased after Conyza canadensis invasion, there was an extremely significant positive correlation among the three elements (P<0.01). Different soil communities at different depths and their interactions have significant effects on soil total nitrogen (P<0.01). N is the factor of limitting the growth of Conyza Canadensis. There is also a significant positive correlation between the three C:N, C:P and N:P in the soil. N:P changes steadily, and C:N, C:P have high levels of variation, it may be related to the great change of soil total carbon content.