The invention discloses an interlocking check nut. The interlocking check nut is mainly used in the machinery field. The interlocking check nut has the interlocking function. The tightened nut is notreleased from a bolt, and manufacturing and use are convenient. The interlocking check nut is composed of a nut body A and a nut body B. According to the working principle and mounting process, the clamping portion of the nut body B is upwards tightened, the lower end of the nut body B compresses a workpiece, the extrusion portion of the nut body A is downwards screwed on the bolt and jacks the clamping portion of the nut body B tightly, a plurality of convex ribs of the extrusion portion of the nut body A extrude a plurality of clamping pieces of the nut body B, inner threads B of the multiple clamping pieces extrude outer threads of the bolt, the outer threads of the bolt are tightly hooped, the anti-looseness purpose is achieved, and at least one convex rib is clamped into a groove of the nut body B in the process, so that interlocking is achieved; and under the function of vibration loads, the nut body A loosens firstly, the convex ribs clamped into the groove of the nut body B also prevent the nut body A from loosening, and at the same time, the multiple convex ribs tightly clamp the outer threads of the bolt, the anti-looseness purpose is achieved.