Although the GM(1,1) model has been successfully adopted in various fields and has been demonstrated promising prospect. But the form of the GM(1,1) model is single and obviously is not suitable for all data with different character. In order to increase the adaptive capability some different forms of the grey model is needed to be established. The paper adopts combinatorial form instead of const in the right part of the grey equation which we call it GSM(1) model. GSM(1) model is one variable index serials function which contains more information in the equation and can find more complicated law between data. On the condition of the original data multiplying the time interval the paper introduces difference quotient into the equation and establishes the unequal GSM(1) model. The examples prove GSM(1) is an effective form to improve the accuracy of the grey model. It provides a new way for the grey system application.