Calculated weights by traditional PCM(pairwise comparison matrix) adjustment methods can′t retain the information of the original PCM to the maximum extent. Therefore, a method for PCM modulation based on the weights was proposed. The method constructed a completely consistent matrix according to the properties of weights, and the matrix was fitted by the AdaGrad method, so as to minimize the total change of the matrix relative to the original PCM. Corresponding weights was taken as the calculation result of the matrix. Numerical results show that this method can significantly improve the retention of original PCM information compared with other methods and does not require repeated consistency checking.