The invention discloses an adhesion control system for a motor train unit. A system for determining slip velocity of a wheel set of the motor train unit is used for carrying out information fusion and reconstruction on obtained wheel set linear velocity, train body velocity and train body accelerated velocity through an improved Sage-Husa self-adaptive Kalman filtering algorithm, judging the train body velocity, the train body accelerated velocity and the wheel set linear velocity, filtering electromagnetic interference of a sensor signal and uncertain mechanical interference through online estimation of measurement noises, obtaining accurate filtered train body velocity and using the filtered train body velocity as a reference velocity for calculating the slip velocity. The adhesion control system for the motor train unit, disclosed by the invention, is advantaged in that the system is conductive to a motor train unit control method using the slip velocity as an important parameter; and the control effect is improved.