The invention discloses a method for predicting the performance of a centrifugal pump serving as a turbine based on an improved artificial neural network. The method comprises the following steps: firstly, calculating the lift HBEP, T and the flow QBEP, T of the optimal working condition point of the pump serving as the turbine at each specific speed in a segmented manner, and calculating the ratio a of the flow Qi to the flow QBEP, T at each working condition point in a turbine state and the square root b of the ratio of the Hi to the HBEP, T corresponding to the Qi; constructing a training set, wherein each training sample comprises geometric parameters, flow, a and b of the centrifugal pump and lift and efficiency corresponding to each flow in a turbine state; constructing an artificial neural network, and simultaneously performing L1 and L2 regularization on the artificial neural network; training the artificial neural network by adopting the training set; and finally, geometric parameters a and b of a to-be-predicted centrifugal pump in a turbine state are input into the trained artificial neural network, and lift and efficiency corresponding to each flow working condition are output. The method is wide in application range, high in prediction precision and short in calculation period.