Exampled by a certain launch vehicle, the modeling method and modelingprocess with Simulink to mathematicalsimulation on three-channel for the vehicle attitude control system are described.The problem of the local surge of the calculated data due to the so-called freeze time method during the simulation process is analyzed and the resolvent is given. Algebraic loop problem encounteredinSimulinkmodeling of this large scale system is discussed and the resolvent is given.