The utility model relates to a mountain region crawler tractor's levelling mechanism based on integral key shaft transmission, including leveling frame, levelling device and traveling frame. The leveling frame includes upper frame, bearing frame 1, bearing frame 2 and hydro -cylinder seat, and bearing frame 1, bearing frame 2 and the welding of hydro -cylinder seat are in upper frame, the levelling device includes the pneumatic cylinder, the driving lever, the driven lever, bearing bar 1, bearing bar 2, the pull rod, integral key shaft 1 and integral key shaft 2, the both ends of pneumatic cylinder respectively with the hydro -cylinder seat, the driving lever is articulated, the other end of driving lever and integral key shaft are 1 through the splined connection, it has the pull rod to articulate between driving lever and the driven lever, the other end of driven lever and integral key shaft are 2 through the splined connection, integral key shaft 1, integral key shaft 2 respectivelywith bearing frame 1, 2 articulated connections of bearing frame, bearing bar 1, the one end of bearing bar 2 respectively with integral key shaft 1, the integral key shaft is 2 through the splined connection, the other end is articulated with traveling frame. The utility model discloses a can improve crawler tractor's stability and the anti ability of tumbling.