Abstract: This paper presents a positive matrix prediction and reverse prediction method of fuzzy Petri net, and design a fault prediction method based on large scale network service system model, through comparing the traditional model and the fault tree method to verify the accuracy of the model and efficiency. An analysis using the probability importance calculation and initial library, through the evolution of hardware and software fault fault of large scale network service system, fault prediction model is practical large-scale network service system to validate the design.