Abstract: The low specific speed centrifugal pump has the characteristics of small flow, high head and low efficiency. In order to improve the efficiency of the low specific speed centrifugal pump under the condition of meeting the use requirements of the head, this paper optimizes the low specific speed centrifugal pump by modifying the meridian surface of the impeller, and then the blade outlet width, the inlet shroud placement angle, the inlet hub placement angle, the outlet placement angle and wrap angle are used as optimization parameters. Head and efficiency are selected as optimization goals. 40 groups of experiments are designed by using the optimal Latin Hypercube Design Method. BP neural network is used as the surrogate model between optimization parameters and optimization goals, and NSGA-Ⅱ multi-objective genetic algorithm is used to optimize the head and efficiency. After optimization, the hump phenomenon is suppressed by chamfering the impeller outlet. The final optimized centrifugal pump has an increase of 13 m in head and an efficiency increase of 8.07% under standard conditions.