Abstract: In the design of wOrk-piece loading with two pins, it is necessary to guarantee not only the feasibility of locating, but also the required accuracy of locating, In this paper, the formulas for calculation of the maximum and minimum allowable values of the minimum clerance between the cylindrical surface of the rhombic pin and the locating hole, derived from the requirements of angular locating accuracy and locating feasibility respectively by probability method are:whereandwher eVIf the value of minimum clearance （J）x selected in actual design satisfies the following condition （J2）x min<（J2）x<（J2）x max it will fulfil the design requirement.