The invention discloses a belt transmission cross full shaft type two-degree-of-freedom universal joint mechanism, and relates to a universal joint mechanism, and the mechanism provided by the invention is used for solving the problems of the existing bevel gear differential coupling universal joint mechanism that the rigid contact exists between a motor speed reducer and a differential action coupling bevel gear, the motor speed reducer is easy to damage, four bevel gears are installed in a cantilever mode, and the bearing capability is worse. A horizontal shaft and a vertical shaft are arranged vertically; a first large belt wheel and a first bevel gear as well as a third bevel gear and a second large belt wheel are arranged symmetrically relative to the horizontal shaft; a central sleeve is positioned between the first bevel gear and the third bevel gear; rolling bearings are respectively arranged between the first large belt wheel and the vertical shaft, between the first bevel gear and the vertical shaft, between a third bevel gear and the vertical shaft and between a second large belt wheel and the vertical shaft; the first large belt wheel is fixedly connected with the first bevel gear; the third bevel gear is fixedly connected with the second large belt wheel; two ends of the vertical shaft are installed on two brackets; and the first large belt wheel is correspondingly connected with a small belt wheel in a transmission mode through a first belt. The universal joint mechanism provided by the invention is used for adjusting the posture of the tail end of an actuator.