The invention provides a radial synchronous-adjusting mechanism for the roller of a pipe mill, so as to solve the problems, in the prior art, that the effect of roller adjusting is bad, the product qualification rate is low during mass production of pipes, and a novel structural way is required for radial adjustment to rolling pipe diameter; the invention adopts the technical point that a mounting framework is fixed on the upper surface of a frame, an inclined wedge mechanism is fixed at the lower part of the mounting framework, a five-rod mechanism is arranged above the inclined wedge mechanism and fixed in the middle of the mounting framework, and three roller mechanisms are further mounted on an arc-shaped inner side formed by the surrounding of the five-rod mechanism; the radial synchronous-adjusting mechanism provided by the invention has the positive effects as follows: adjustment to radial positions of the rollers can be achieved according to needs, so as to meet the requirements of producing different products, the rollers can be contracted and released at the same time through the five-rod synchronous mechanism, radial positioning is accurate, and the product qualification rate is ensured; the invention further has the characteristics of high control degrees, low cost, stability, reliability and stronger practicability and the like.