When rate limiter is saturated in flight control systemtime delay would occur.The pilot induced oscillations (PIO) may come into being on condition that the pilot operates incorrectly.A simplified model of rate limiter was establishedand the switching suppresser designed by using logical conditions method was anatomized.The response properties of the openloop frequency and phase compensation ability of the suppresser were studied by using describing function.The openloop response properties of the suppresser to sine wave and bias input were discussed.A switching suppresser to prevent PIO was proposedand a mathematical model of closedloop aircraftpilot system with the derivative switching suppresser was set up.The step tracking tasks were simulated to study the performance the switching suppresser and DASA anticipatory control suppresser.The simulating results demonstrate that derivative switching suppresser effectively reduces the possibility of PIO.