Commonly reported in some literature its sewage pump and slurry pump has a high water efficiency, and some even close to the efficiency of water pump, I have the following views: (1) With the continuous improvement of theoretical research and experimental conclusions of the deepening and accumulation , Especially the application of two-phase flow theory, it is inevitable that the efficiency of sewage pump and slurry pump should be constantly improved. (2) Ordinary water pumps are designed for maximum efficiency, that is, the hydraulic structure parameters of a water pump are the best combination for maximum efficiency. For sewage pumps, slurry pumps and other special requirements of the pump efficiency can not exceed the same period of the efficiency of the pump. This comparison refers to the advanced level of contemporary rather than a person's level of design. (3) sewage pump, slurry pump efficiency is lower than the main reason for the pump is their over-flow channel widened. The decrease in efficiency is mainly related to the degree of broadening. Therefore, it is meaningless to compare the efficiency of two different sewage pumps and slurry pumps (Q, H, n) without the limitation of capacity. (4) The widening of the sewage pump runner is to prevent clogging, so the efficiency of the original sewage pump is usually lower than that of the secondary sewage pump. The author according to φ / DS = 0.6 ~ 0.8 and Q η = 0.78- (6.74Q) -0.32-0.29 (0.32-lg0.013ns) 2 where Q - flow, m3 / h. φ - pump allows the size, mm. (5) Mud pump channel widening is mainly to reduce the velocity of flow in the two-phase flow channel to reduce wear and tear. Therefore, the strong abrasive slurry pump efficiency is usually lower than the efficiency of the soft mud pump. Such as Zigong Industrial Pump Co., Ltd. produced NG, ND pump is used for strong abrasive slurry, NQ pump is used to pump light mud. (6) It is suggested that given the efficiency of the sewage pump and the slurry pump, the minimum passing size is given to facilitate the comparison of the pump design level. It is suggested to establish the relationship of η = f (Q, ns, φ) sewage pump and slurry pump by experiment.