Inner diameter detection device

The inner diameter detection device comprises a detection part (1) which is used for detecting the inner diameter of a clutch cylinder body groove (12) in a clutch cylinder body (11), is of a hollow cylindrical structure and can be arranged in the clutch cylinder body groove (12); a first fixed body (2), a second fixed body (3) and a first movable body (4) which are used for detecting the inner diameter in a clutch cylinder body groove (12) are arranged on the outer side wall of the detection part (1). Wherein the first fixed body (2), the second fixed body (3) and the first movable body (4) are arranged on the same plane, and a detector (5) used for detecting the inner diameter state is arranged outside the first movable body (4); the device has the effects that the inner diameter of thestep in the middle is detected, the inner diameter of the clutch cylinder body groove (12) in the clutch cylinder body (11) is detected in the mode that three-point positioning is adopted to determinea plane, the structure is