The invention discloses a blade profile size control method, which comprises the following steps of: 1, selecting n blade sections from a blade tip of a blade to a joint of a blade body and a tenon root, namely S1, S2,... Sn, wherein n is a positive integer; 2, measuring the distance Hn from the section of each blade to the joint of the blade body and the tenon root; measuring the length H of thewhole blade body; 3, respectively substituting Hn and H into a formula; obtaining the offset Ln of the blade profile after the section Sn of the blade is subjected to wax mould placing and shrinking;wherein the maximum blade profile offset L of the joint of the blade body and the tenon root after wax mould placing and shrinking is a known amount; and 4, adopting the offset Ln to control the finaloffset of the section Sn of the blade when the blade is manufactured. The fatigue performance of the joint of the blade body and the tenon root is not reduced, the blade profile size design requirement and the blade weight requirement are met within the blade size tolerance range, and the blade cannot exceed the design weight.