Aiming at the field of non-member mass concrete structure design，we take the side pier wall of compound lock chamber of the second lock for Honghua water control project in Liujiang as an example，compare and analyze the traditional hand calculation method and finite element method about internal force and reinforcement calculation. The results show that the finite element stress integral method is suitable for calculating the bending moment of the traditional member structure. As a mass concrete structure of non-member system，the side pier wall of lock chamber has a large section height and a large proportion of the compression area，and the neutral axis is inclined to the tension area. The bending moment calculated by stress integral method is too large. The traditional hand calculation method and the finite element stress integral method are used to calculate the internal force，and the reinforcement requires a large number of tensile reinforcements and is not economical when calculating by the compression bearing capacity of the normal section of the eccentric compression member with rectangular section. The tensile stress of concrete in the tension area analyzed by the finite element elastic stress graph method is completely borne by the tensile reinforcement. According to the reinforcement calculation principle of non-member system reinforced concrete structure，the actual amount of tensile reinforcement is reasonable and economical.