The invention relates to a locking device for a machine tool in mechanical manufacturing equipment, in particular to an interlocking device for a slant bed body and a tailstock of a numerical control lathe. The interlocking device comprises a lock body, wherein the lock body is provided with a hollow cavity; an eccentric shaft is connected in the cavity through a bearing arranged on the outer wall of the lock body; a pull rod is sleeved on the middle part of the eccentric shaft; the pull rod is connected with a compaction pressing plate of the hydraulic tailstock at the lower end of the lock body into a whole through a bolt; the shaft surface of the eccentric shaft on one side of the pull rod is provided with a semicircular clamping groove; an interlocking shaft vertical to the horizontal direction of the eccentric shaft is arranged in the semicircular clamping groove; the interlocking shaft is connected with the semicircular clamping groove through a gap matched with the semicircular clamping groove; one shaft end of the interlocking shaft passing out of the lock body is connected with a tailstock pulling block; and the eccentric shaft on the other side of the pull rod is connected with a locking pin passing through the lock body. Due to the structure, the interlocking device has the advantages of realizing interlocking between the slant bed body and the tailstock, further improving the production efficiency and reducing the using cost.