The invention discloses a rubber crawler hydraulic tensioning device with oil-charging and pressurizing functions for a mountain crawler tractor. The device comprises a hydraulic oil meter, a four-wayjoint, a rear cylinder oil pipe, a rear hydraulic oil cylinder, a rear hydraulic cylinder fixing frame, a pressure-reinforcing operation handle, an oil-charging and pressure-reinforcing device, a front hydraulic cylinder fixing frame, a front hydraulic cylinder and a front cylinder oil pipe; four outlets of the four-way joint are connected with the oil-charging and pressure-reinforcing device, the hydraulic oil meter, one end of the front cylinder oil pipe and one end of the rear cylinder oil pipe respectively; a piston rod of the front hydraulic cylinder is connected with a guiding wheel, alug of the hydraulic cylinder is connected with the front hydraulic cylinder fixing frame, a piston rod of the rear hydraulic oil cylinder is connected with the rear hydraulic cylinder fixing frame, and a lug is connected with a main connecting rod. The rubber crawler hydraulic tensioning device with the oil-charging and pressurizing functions for the mountain crawler tractor has the advantages that tensioning requirements of a rubber crawler of the mountain crawler tractor can be met, it is ensured that the rubber crawler does not fall off when the tractor walks, thereby achieving the dual functions of cushioning and tensioning, achieving the oil-charging and pressure-reinforcing functions, and effectively solving the problem of crawler looseness caused by oil line leakage.