The prediction accuracy of subgrade settlement is not high and the applicability of prediction method is not strong. Based on the combination forecast theory,with the help of MATLAB software,GM(1,1)-Hoshino Nori combination forecasting model is proposed. This model is based on the grey theory GM(1,1) forecasting model linear combination model and Hoshino Nori settlement prediction,taking the combination forecasting error square as standard to determine the weight coefficients of two kinds of prediction methods and minimum standards. With the Guangdong highway construction period and operation period of subgrade settlement data,GM(1,1)-Hoshino Nori combination forecasting model prediction results are better than the two methods separately predicted results. The present method has higher prediction precision,stronger engineering application.