The invention provides a thread beating and slacking structure of a sewing machine and belongs to the technical field of sewing equipment. The thread beating and slacking structure of the sewing machine solves the technical problem that existing thread beating and slacking structures are large in the number of connecting parts, insufficient in stability and reliability and the like. The sewing machine comprises a machine case and a thread clamping module; the thread beating and slacking structure comprises a support rack and a thread slacking plate, wherein the thread slacking plate is provided with a thread slacking lug corresponding to the thread clamping module; the machine case is connected with a thread slacking crank through a shoulder screw and provided with a bidirectional drivingunit, the bidirectional driving unit is provided with a driving rod capable of moving in both directions; the support rack is provided with a thread beating rack which is fixedly provided with a thread beating hook; one end of the thread slacking crank is in contact with one end of the driving rod, and the other end of the thread slacking crank is connected with the thread beating rack; the threadslacking crank is also provided with a pushing unit capable of driving the thread slacking plate to move; the other end of the driving rod abuts against the thread slacking plate and can push the thread slacking plate to move. The thread beating and slacking structure of the sewing machine achieves a dual-slacking function, reduces the number of connecting parts, and meanwhile is simple in installation and stable in operation.