The invention relates to the technical field of bridge maintenance, and discloses a high-pressure grouting device for bridge bottom reinforcement under high temperature environment, Including groutingchamber, Slurry inlet pipe, slurry guide pipe, casing, surge chamber, breathable diaphragm, pressure regulator, Two cooling mechanisms, a metering chamber, a slurry outlet pipe and a circulation hole, wherein the slurry inlet pipe is fixedly communicated with the left end of the slurry injection chamber, the slurry guide pipe is fixedly communicated with the right end of the slurry injection chamber, the sleeve is fixedly sleeved on the outer surface of the slurry inlet pipe, the surge chamber is fixedly sleeved on the outer surface of the sleeve and the slurry guide pipe, and the air permeable diaphragm is fixed on the middle of the top wall of the slurry injection chamber. The air pressure in the grouting chamber can be dredged from the two exhaust holes, the air intensity difference inside and outside the grouting chamber can be reduced, the grouting chamber can be prevented from cracking due to the larger pressure difference, the airflow flow rate between the grouting chamber andthe surge chamber can be accelerated, the temperature on the outer surface of the grouting chamber can be rapidly evaporated, and the effect of lowering the temperature of the grouting chamber can beachieved.