According to locking and convenient release requirements of the workpiece with planar three roller centering fixture, the influence degree of the fixture structure parameters tolerance to the inner hole size precision of the workpiece was analyzed, the tolerance calculation methods of the roller diameter and center distance of the wedge surface to the mandrel were put forward. The conclusions are: the size of the inner hole of the workpiece must satisfy a certain precision; the accuracy class of inner hole is related not only with the manufacturing precision of the roller and the center distance of the wedge surface to the mandrel, but also with the workpiece inner diameter, and the diameter is greater, the precision grade required is lower. The research provides reference for the plane three roller centering fixture design.