Abstract: The perpendicular maneuver under water of submarines is a complex multivariable system with coupling. According to the intelligent control theory and idea with expert system techniques, a new type of intelligent controller for automatic change of depth was designed. It was verified by simulation experiment and in-situ test on the sea that this controller not only could deal with strong nonlinearity and multivariable coupling, but also had strong adaptability for a wide range of parameters of the system and disturbance.