Based on the theory of variable weight, the authors used the weight of the state vector measured by the divergence degree to regulate the demand force, the weight of the variable state vector identified by the adjustment degree regulated the supply force, and the weight level of the adjustment weight weighed the balance point between the two so as to select the appropriate state. Change vector, a comprehensive evaluation model of soil nutrient geochemical transformation power, was constructed to solve the problem of evaluation distortion due to the difficulty of highlighting the restrictive effect of nutrient element. The results show that the method is easy to operate and can reflect the changing law of soil nutrient element. The weight vector of product and sum state is difficult to control because of its adjustment degree, and its application range is limited. However, the adjustment degree of exponential state variable vector varies with parameters, the adjustment effect is easy to control, and the application is wide, and it has a good change effect. The soil nutrient data in the pagoda area has low dispersion and high equilibrium. The comprehensive determination of the weight adjustment level is 0.8, the power parameter α= 2.524 8, and the weight is transferred to N and Corg. The penalty is reasonable, and the comprehensive evaluation level of soil nutrients is scientifically adjusted. The grade changes from second class to third class, 42 third class to fourth class, and 131 fourth class to fifth grade, and N and Corg are identifiedas the short plate elements of soil nutrients in the pagoda area which overall limit the improvement of soil nutrient quality.The results obtained by the authors providea necessary basis for scientific improvement of the soil under local conditions.