The invention provides a prosthesis locking assembly for tibia and an artificial knee joint prosthesis, which relate to the technical field of medical instruments, the prosthesis locking assembly comprises a tibia platform, a tibia liner and a fixing part; the tibia liner is clamped on the tibia platform, the movement of the tibia liner is limited, the tibia liner is prevented from moving away from the tibia platform; meanwhile, the fixing part is inserted into a fixing groove defined between the tibia platform and the tibia liner; resistance for preventing the tibia liner from rotating relative to the tibia platform is formed; the tibia liner is fixed on the tibia platform, the problem that in the prior art, a locking structure between a tibia support and the tibia liner is complex is solved. The thin wall and the thin groove can weaken the connection firmness between the tibia support and the tibia liner, abrasion can be caused after long-time use, connection is not firm, and the service life is short are solved, and the technical effects that the locking structure between the tibia platform and the tibia liner is simplified, the connection firmness is improved, and the service life of the tibia prosthesis is effectively prolonged are achieved.