The invention relates to a connecting structure for pipe fittings. The connecting structure is arranged on a valve body, and comprises at least one connecting pipe; each connecting pipe is provided with a connector connected with an external pipe fitting; the end face of the connector is provided with a boss; and the diameter of the inner end face of the boss is greater than that of the outer end face of the boss. The connecting structure for the pipe fittings has a simple structure and convenience in connection. Moreover, the pipe diameters of the connecting pipes are different in size, therefore, the goal that thick pipes get in and thin pipes get out or the thin pipes get in and the thick pipes get out can be achieved, and the flow of the connecting pipes is conveniently controlled.