The invention discloses a hardening and tempering method for a 12Cr13 stainless steel bar and aims to provide a method which guarantees the mechanical properties, also lowers the production cost and improves the production efficiency. The hardening and tempering method disclosed by the invention is characterized in that a thermal treatment process for hardening and tempering is optimized, namely an incomplete annealing pretreatment process is added before hardening and tempering, subsequently a desk type furnace/a continuous heating furnace is used for carrying out (hardening + tempering) hardening and tempering, straightening and stress relief annealing, wherein the 0-DEG-C impact value of the bar after straightening and stress relief annealing is not large in change; and finally the mechanical properties of the 12Cr13 bar totally meet the standard requirements of nuclear power materials. By using the hardening and tempering method disclosed by the invention, even a traditional heating furnace is adopted for carrying out hardening and tempering treatment on the bar, the mechanical properties can still meet the requirements of the standard nuclear power hardened and tempered 12Cr13, especially the o-DEG-C impact value is quite large in increment range and the numerical value fluctuates stably; after thermal treatment, the deviation of the hardness (HBW) of the overall bar is not larger than 15; the thermal treatment cost is lowered; and the production efficiency is improved.