Abstract: In order to effectively solve the problems consisted in the method of existing network system fault detection, the problems includes that detection accuracy is not high, the detection convergence speed is slow, and it's easy to fall into local optimum.In this paper combined with the Bat Algorithm(BA)and Quasi Newton(QN)strategy, a novel model of network system fault detection based on QN-BA is proposed.In this way, the optimal solution of the model is obtained by combining the filtering model and the residual error model, which can effectively avoid the existing problems.Finally through the simulation experiment obtained the fault detection performance index chart, and by comparing the NPSO-PF and LWRLR verify the effectiveness of the proposed approach.