In accordance with the strict demand of Performance Based Navigation (PBN) on navigation performance monitoring a set of integrity monitoring algorithm for integrated GNSS/SINS system was presented for increasing the fault detection efficiency.Based on which a combined parallel filtering algorithm was used for fault exclusion.The simulation results showed that by using the algorithm both GNSS and Inertial Measurement Unit (IMU) failure can be detected and the detecting efficiency for Slowly Growing Errors (SGEs) was improved.In addition the algorithm is adaptable to multiple measurement failures.