Provided is an underwater robot monitoring auxiliary device. The device comprises a cylindrical shell, guide rails, a bearing column, a stop plate, a connecting strip and a butt sleeve, wherein the cylindrical shell is nested inside the butt sleeve; the cylindrical wall of the cylindrical shell is provided with a notch; the two ends of each guide rail are mounted onto the inner wall of the butt sleeve and each guide rail passes through the notch in the cylindrical wall of the cylindrical shell; the bearing column is arranged at the bottom of the cylindrical shell; one end of the stop plate is mounted onto the top of the butt sleeve; one end of the connecting strip is fixed onto the inner wall of the cylindrical shell; and the other end of the connecting strip is fixed onto the outer wall of the butt sleeve. An observation cylinder is additionally arranged inside the butt sleeve so as to facilitate the observation of a robot through the ejected observation cylinder; at the same time, a better opportunity is provided for putting down a conduit rack so that the robot is prevented from walking back and forth in water for observing whether two guide posts enter the butt sleeve of the conduit rack correctly, and accordingly the sitting opportunity of the conduit rack is not missed.