Abstract: An improved response surface method is proposed based on a reasonable selection of experimental points. The experimental points are selected in a tangent plane through the design point, and these experimental points are moved along the normal vector of the tangent plane. The reinforced experimental points are selected by using the information of the design point and the experimental point selected previously. The experimental points of the proposed method focus on the design point and consider the trend of the limit state function (LSF) around the region of a design point, so that the fitting precision of a response surface function (RSF) to the LSF around the region of the design point is increased. In the process of the fitting of RSF, in order to improve the evaluation accuracy of failure probability, the proposed method can guarantee that there is no error between the RSF and LSF at the design point. Examples given have demonstrated the efficiency and the accuracy of the proposed method for both numerical and implicit LSFs.