Abstract: A new leak monitoring method based on integration neural networks (INN) and the fuzzy logic fusion (FLF) was proposed to solve the problem of pressurizer leak monitoring. In this approach, a pressurizer leaking diagnosis model was established by a radial basis function neural network (RBF-NN). Two Elman neural networks (Elman-NN) were used to establish pressurizer parameters prediction model and pressurizer leak diagnosis model respectively. Then, the fuzzy logical method was used to fuse the diagnosed results of RBF-NN and Elman-NN. The fusion results were the final monitoring results. The nuclear power simulator was used to test the feasibility of the proposed method. The results show that compared with the diagnosis method based on single neural network, the proposed method is simple and reliable.