The invention provides a coupling capable of achieving good cooling. The coupling comprises a coupling body, a first annular bulge, a second annular bulge, a first circular ring part and a second circular ring part, wherein the coupling body is a hollow cylinder; a first annular opening is formed in the outer wall of the first annular bulge; two first slide rails are symmetrically arranged on the upper and lower walls of the first annular opening; a second annular opening is formed in the outer wall of the second annular bulge; two second slide rails are symmetrically arranged on the upper and lower walls of the second annular opening; a cooling cavity is integrately formed in the side wall of the coupling body, the first annular bulge and the second annular bulge; two first clamping edges are symmetrically arranged on the upper and lower surfaces of the first circular ring part; a water inlet is formed in the first circular ring part; the first clamping edges are rotatably arranged in the first slide rails; two second clamping edges are arranged, symmetrical about the second circular ring part, on the upper and lower surfaces of the second circular ring part; a water outlet is formed in the second circular ring part; and the second clamping edges are rotatably arranged in the second slide rails. The coupling capable of achieving good cooling has a good cooling effect and an effect of resisting radial motion.