An artificial joint fixation mechanism has a base for being attached to an artificial joint, a stem for guiding an artificial joint to engage with a human bone, and a sleeve. The base defines a conic shaft hole therethrough. At least a positioning section and at least a threaded section are extended adjacent an end of the shaft hole. The stem includes an engaging pole at an end thereof for jointing to an artificial joint. The sleeve is threaded for screwing to the threaded section and defines an inner cone hole therethrough. In use, the engaging pole of the stem implants into the shaft hole. The sleeve is screwed to the threaded section, and the inner cone hole reversely pressing against the guiding section. Thus the stem is pressed reliably.