The invention belongs to the technical field of medical instruments and particularly relates to the technical field of interventional instruments in third-class medical instruments, in particular to a transcatheter heart annuloplasty system. The transcatheter heart annuloplasty system comprises a forming ring assembly, wherein the forming ring assembly comprises a macromolecular braided tube, an anchor nail, a contraction line and a bidirectional contraction device; a delivery assembly, wherein the delivery assembly is used for conveying the forming ring assembly to a target position; and a continuous anchoring assembly, wherein the continuous anchoring assembly is used for fixing the forming ring assembly to the target position. Through the bidirectional contraction device based on a compression spring, a friction disc and a wire spool, bidirectional contraction of a forming ring fixed to a valve is achieved, the strength and size of contraction of the valve are accurately adjusted, locking can be achieved at any time, a doctor is allowed to adjust the contraction degree of the valve according to different conditions of different patients, and the doctor is allowed to make adjustment in an opposite direction, so that the size change of the valve during continuous opening and closing is adapted, thus, the success rate of an operation is guaranteed, and secondary operation correction is avoided.