The invention discloses a prestressed reinforcement with a yield plateau, and its prestressed member construction method. The prestressed reinforcement comprises 0.456-0.49wt% of C, 1.95-2.43wt% of Mn, 0.65-0.7wt% of Si, 0.24-0.35wt% of Cr, 0.02-0.07wt% of V, 0.013wt% of S, 0.027wt% of P, 0.34-0.37wt% of Ni, 0.05-0.06wt% of Al, 0.28-0.3wt% of Nb, 0.015-0.019wt% of Ti, and the balance Fe and inevitable impurities. The construction method of a prestressed member is characterized in that the prestressed member is obtained by applying prestress having a value accounting for 30-70% of a tensile strength is applied to the restressed reinforcement with a yield plateau through a pre-tensioning method or a post-tensioning method. The method substitutes present technological construction methods, and the consumption of regular reinforcement is reduced by above 70%.