In inertial navigation system, the error accumulation of altitude is unsteady, so the outside information sources such as barometric altimeter, etc. should be used to damp the accumulation. In this paper, how to design a net of altitude-damper, how to determine the parameters in the net and how to deal with the net in Kalman Filter of the integrated navigation system are discussed respectively by adopting the method of Monter-Carlo emulation to imitate the strapped-down navigation system and INS / GNSS integrated navigation system. And finally the actual result of the emulation is given.