The invention provides a correcting method for an R-shaped transformer core unfolded belt numerical control cutting curve. Relevant parameters in the correcting method for the R-type transformer core unfolded belt numerical control cutting curve are corrected, thus the correction on core quality and section diameter is realized, and the problem of over high scrap rate caused by the condition that the core quality and the section diameter do not reach the standard is solved. The core content of the algorithm is as follow: (1) the input of initial data; (2) the mathematical model establishment of an R-shaped core unfolded belt curve; (3) the correction of core section diameter; (4) the collection of core quality; (5) the fine adjustment of the section diameter; and (6) the output of the correction data. The invention can be used for any winding type core with round section or elliptical section, such as an R shape, a three-phase symmetrical triangle, a three-phase Chinese character Ri shape, an elliptical three-dimensional triangle, and the like; and the algorithm has great flexibility and practicability.