The invention relates to a cam-type variable-diameter drifting connector and a use method. The connector at least comprises a shell, a pin penetrates the front side and the rear side of the shell, sothat an O-shaped ring is arranged on the shell, one end of a wing rib is rotatably connected on the shell, a ball is arranged below the wing rib, a cam rotating sleeve, a curved surface positioning sleeve, a guide sleeve, an investment sleeve, a guide key, a positioning ring and a spring are arrange din the shell, the curved surface positioning sleeve is fixedly connected with the lowermost end ofthe inner surface of the shell, the cam rotating sleeve and the spring are mutually connected in a combined manner and connected in the curved surface positioning sleeve in an embedded manner, the inner upper end of the cam rotating sleeve are inserted into the lower end of the investment sleeve, the top end of the investment sleeve is locked by the positioning ring, the guide sleeve and the guide key are mutually and fixedly connected and fixedly connected on the inner wall of the upper end of the shell, an annular cavity is formed in the guide sleeve and the guide key, the upper end of theinvestment sleeve is inserted into the annular cavity, the inner surfaces of the guide sleeve and the guide key are connected with the outer surface of the cam rotating sleeve in an embedded manner, the device can achieve drilling and drifting once without replacing a drilling tool, and a drilling period is shortened.