The invention discloses a semi-open impeller pump with a sealing cover plate structure, which comprises a pump casing and a pump rear cover, an impeller and a pump shaft which are installed in the pump casing, and a motor which is arranged on the outer side of the pump casing. The impeller is installed on the pump shaft and is driven by the motor to rotate; and an inlet pipe and an outlet pipe are arranged on the pump casing. The impeller adopts a semi-open structure and comprises a vane, a wheel hub and a rear cover plate and is characterized in that the inlet pipe extends into the inner part of the pump casing from the outer part of the pump casing; the rear end of the inlet pipe is positioned at the front end of the vane of the impeller and shares one shaft with the pump shaft; and a ring-shaped sealing cover plate is installed at the rear end of the inlet pipe; the end surface of the sealing cover plate is parallel with the front end surface of the vane, and end cover sealing is formed between the both. The molded line of the vane adopts a variable camber curve, the camber of the curve is gradually reduced from the inlet to the outlet, and the camber is minimal at the outlet. The semi-open impeller pump has the advantages of simple manufacture process, convenient processing, low cost, stable structure, good passing ability of solid particle, smooth overflowing and high efficiency.