The utility model discloses an angular bearing box for mounting a rail-mounted hoisting machinery supporting wheel. The device comprises a bearing box which is round inside and square outside as a whole and is provided with a group of opposite angles which are respectively an arc angle and a chamfer, a positioning groove I used for clamping a positioning block I is formed in the horizontal top face connected with the chamfer, a positioning groove II used for clamping a positioning block II is formed in the vertical surface of the right side connected with the chamfer, and a fixing pin is installed between the positioning block II and the bearing box. A slope groove I and a slope groove II which correspond to each other are machined in the middle positions of the other set of opposite angles of the bearing box respectively, a wedge block I matched with the slope groove I is arranged on the bottom face of the left end of the positioning block I, and a wedge block II matched with the slope groove II is arranged on the left side face of the bottom of the positioning block II. The utility model has the characteristics of simple structure, easiness in manufacturing, convenience in assembly and maintenance, light weight, material saving, economy and practicability. Modularized, light-weight and serialized model selection can also be realized.