In this work, a bimodal grain structure was developed for commercial purity Ti(CP-Ti) via powder metallurgy processing,followed by free hot forging and then heat treatment. The bi-modal grains were characterized with electron backscatterdiffraction. The mechanical tests showed that in comparison to the uniform and equiaxed grain structure, the bimodalgrains improved the yield strength of CP-Ti significantly, while it maintains a merely changed ultimate tensile strength andelongation to failure. In addition, an interesting yield plateau was observed in the bimodal CP-Ti. To explore underlyingmechanisms behind the phenomenon, the microstructures of the samples before and after testing were carefully examined. The results revealed that geometrically necessary dislocations accumulating at the interface between coarse and fine grainsinduced back stress hardening, which together with the statistically stored dislocations also accounted for the yield plateauin the bimodal CP-Ti.