The static bending test of 5 concrete trabeculas cut from two large prefabricated members is carried out, and the parameters such as reinforcement ratio and deflection of longitudinal reinforcement are studied, and the mechanical characteristics of the members and the bearing capacity of the normal section are analyzed in combination with the current code, cracks and deflection. The results show that: (1)The stress characteristics of cut trabeculae are the same as those of ordinary reinforced concrete beams, and the average strain of concrete keeps plane along the section; (2)Tthe deflection of longitudinal tendons and the reinforcement ratio of upper longitudinal tendons have no significant effect on the bearing capacity of members; (3) The maximum crack width and the average crack spacing are in agreement with the calculated values of the code, which can be calculated according to the current code; (4)Tthe crack width and deflection meet the requirements of the current code.