The research of soil classification and soil grade evaluation is often based on fuzzy theory. So the traditional method has an inevitable problem about weight matrix which given by some experts. The finally result can be influenced by artificial factor. A new technique of falling dimension named projection pursuit is applied to soil study through using the improved real coding based accelerating genetic algorithm to optimize the projection direction. Thus

it can transfer multi dimension data into one dimension data

through searching for the optimum projection direction to realize the soil classification and its grade evaluation. The method can avoid the artificial disturb

and acquire preferably effect. Thus

it provides a new method to the research of soil classification and grade evaluation.