Abstract: NPR (Negative Poisson ratio) rein is a new type of high strength rein, the standard value of yield strength is greater than 625 MPa, and the tensile strength and compressive strength are different. In order to research the application of NPR rein in concrete flexural members, based on the constitutive relation of the rein, the limited compression height is derived by the assumption of plane section. The maximum reinforcement ratio of a single reinforced beam and the relative relationship between the compression reinforcement and the tension reinforcement of a double reinforced beam are derived. The calculation method of normal section of flexural member is derived. The results show that the calculation method of NPR reinforcement is different from that of ordinary hot-rolled reinforcement for concrete flexural members. The problems existing in the existing structural calculation software are put forward, and the treatment measures for the rectangular section flexural members with NPR rein are put forward. The research results can provide reference for the popularization and application of NPR reinforcement in engineering.