The invention discloses an efficient grid milling method for an inner curved surface of a tapered revolving body. The efficient grid milling method comprises the following steps: 1) conducting coarse milling on the inner curved surface of the tapered revolving body; 2) conducting heat treatment on the tapered revolving body so as to control the roundness deformation to be within 2 mm; 3) conducting semi-fine milling on the inner surface of the tapered revolving body, wherein the allowance in the inner surface is 0.7 to 1.3 mm; 4) conducting artificial ageing treatment on the tapered revolving body to remove stress generated during coarse milling and semi-fine milling of the tapered revolving body; 5) conducting fine milling on the inner surface of the tapered revolving body till the wall thickness achieves the design size. Due to semi-fine milling, artificial ageing treatment and reasonable machining allowance distribution, problems of part deformation, uneven wall thickness and poor roundness of the tapered revolving body are solved; the product processing efficiency is improved by designing cutting parameter and tool path, wherein the part processing efficiency is improved by 2 to 3 times, the part qualified rate is improved from 70 percent to higher than 97 percent.