Coupler facilitating limitation of adjustable range

The invention discloses a coupler facilitating limitation of an adjustable range. The coupler comprises a main coupler body, a connecting block, a center plate, a cylindrical pin and a reset spring, and the connecting block is clamped on the outer surface of the main coupler body; the center plate and a secondary coupler body are fixedly installed on the outer surface of the connecting block; anda limiting groove is formed in the outer surface of the secondary coupler body, and a sliding groove is formed in the inner surface of the connecting block. According to the coupler facilitating limitation of the adjustable range, an adjustable shaft body locking ring is arranged, and is easy to install in the coupler through a buckle installed on the outer surface of the shaft body locking ring,and both the inner surface of the shaft body locking ring and the inner surface of the coupler are provided with built-in grooves; movable blocks can be installed on the inner surfaces of the built-ingrooves slidably, and loca