The invention relates to a method for correcting the tooth profile error of a cycloidal gear and a cycloidal gear, belonging to the technical field of manufacturing the cycloidal gear. A mathematicalmodel of the cycloidal gear tooth surface generation grin motion is established to determine the mutual influence relationship between the machine tool grin parameters and the actual tooth profile error, and a digital back-adjustment correction mathematical model is established to further solve the optimum machine tool grinding paramete correction amount and the final machine tool grinding adjustment parameter. The invention solves the problems of qualitative and quantitative correction in the traditional machining process, repeated adjustment and trial cutting, and the like, effectively improves the tooth profile machining accuracy of the cycloidal gear, the tooth profile machining error after one correction can reach the engineering requirements, and shortens the product manufacturing cycle of the cycloidal gear.