Out-of-roundness control method for short-stress-path rolling mill

The invention discloses an out-of-roundness control method for a short-stress-path rolling mill. The out-of-roundness control method comprises the following step (1) of designing the size, close to the size of a finished product, of a K3 rolled piece in a rolling procedure; the step (2) of designing a true circle K2 pass, and using a finished circle-circle pass for circle gauging; adopting a circle gauging process of ellipse-circle-circle-circle true circle pass for four passes K4, K3, K2 and K1; the step (3) of modifying a K1 final pass for ensuring that the size of two shoulders of the passis larger 0.5 mm than the size of the groove bottom of the pass; the step (4) of modifying K1 guide wheels, and ensuring that a standard K2 material pattern is consistent with the R arc of the K1 guide wheels, and the material pattern is completely fit with the guide wheel for improving the support effect when the material pattern is clamped by the guide wheels; the step (5) of using double rows of guides for K1 inlet gui