To improve the accuracy of biaxial bending member reinforcement design，we analyze the ultimate limit states capacity of the reinforced concrete arbitrary sections based on Eurocode 2，calculate the reinforced concrete normal section capacity with an efficient dynamic mesh update technique and a Gaussian integration method according to the segmented characteristics of stress-strain relationship of reinforced concrete materials，and write the related program. The compiled computer program can analyze the ultimate limit states capacity of reinforced concrete arbitrary sections，give three-dimensional envelope surface data，and analyze the feasibility of reinforcement in conjunction with the internal force results of the finite element full node. The results show that this method has fast calculation，high accuracy，and solves the problem of convenience and completeness with a single node result check.