A connecting base for a pump comprises a connecting base frame mainly composed of a cylinder. One side edge of the cylinder of the connecting base frame is connected with a first flange plate used for connecting a pump body. A plurality of evenly-distributed first connecting holes are formed in the first flange plate. The inner side edge of a middle circular hole of the first flange plate is connected with a shaft base sleeve which is contracted in the cylinder and used for installing a rotating shaft mechanical sealing device. A shaft base hole for a rotating shaft or a motor shaft to penetrate is formed in the inner end edge of the shaft base sleeve. The other side edge of the cylinder of the connecting base frame is connected with a second flange plate used for connecting a motor, and a plurality of evenly-distributed second connecting holes are further formed in the second flange plate. A circular ring protruding outwards is arranged on the periphery of the circular hole, located in the outer end portion of the shaft base sleeve, of the first flange plate, and evenly-distributed connecting bolt holes used for fixing the rotating shaft mechanical sealing device are formed in the circular ring face. The connecting base has the beneficial effects that the structure is simple, installing and using are convenient, the motor and an impeller can be reliably connected, the connecting stability, coaxiality and sealing performance are good, a standard motor can be conveniently replaced for maintenance, the stamping resistance of the pump is improved, and the service life of the pump is prolonged.