Abstract: The effect of fertilization levels and different soil organisms on the rate of wheat straw decomposition was studied by using the nylon bag method.Based on obtained data, a non-linear mathematical model of farm organic matter decomposition is developed using the data fitting method of DUD arithmetic.Regression square sum and residual square sum of the model indicate high fitting precisions,and an adopted non-linear mathematical model completely depictes the nature of organic matter decomposition.It is a new and excellent method in the study of soil ecological system modeling and in rationally using organic offal.