The invention relates to a pump, in particular to a dual-shell small-flow centrifugal pump. The technical scheme provided by the invention is that: the dual-shell small-flow centrifugal pump comprises a pump body, a shaft seal device, a pump cover, a revolving shaft and an impeller, wherein the pump cover is arranged between the pump body and the shaft seal device; a flow channel is formed between the pump body and the pump cover; the pump body is provided with a medium inlet and a medium outlet which are communicated with each other through the flow channel; the impeller is in linkage connection with the revolving shaft and extends into the flow channel; the impeller is an open impeller; a pump body lining and a pump cover lining are arranged in the flow channel; the medium outlet is communicated with the flow channel through a diffusion hole formed on the pump body lining; the diffusion hole is conical; one end which is connected with the medium outlet is a large end, and one end which is connected with the flow channel is a small end; the flow channel is matched with the profile of the impeller; and the cross section of the flow channel is cylindrical. Due to the adoption of the technical scheme, a dual-shell small-flow centrifugal pump which has long service life and a simple structure, and is suitable for conveying particle mediums is provided.