The invention provides a mechanical seal flushing device for a slurry pump of a chemical reaction kettle, and belongs to the technical field of flushing device of slurry pumps of chemical reaction kettles. The mechanical seal flushing device comprises a flushing pipeline, a liquid storage tank, a main booster pump assembly, a liquid level control mechanism and a main booster pump electromagnetic valve, wherein the flushing pipeline is arranged on a machine sealing part and is used for flushing the machine sealing part, the liquid storage tank supplies liquid to the flushing pipeline, a primarymain supercharging pipeline and a secondary main pressurizing pipeline are arranged in the main booster pump assembly, the main booster pump assembly can generate different pressures, the different pressures are used for flushing the machine sealing part, the liquid level control mechanism guarantees the stability of the liquid level of the liquid storage tank, the main booster pump electromagnetic valve is controlled by a controller, and can control the opening and closing of the main booster pump assembly. The automatic flushing of the machine sealing part is realized through the control ofthe controller, the automation of process control is improved, the failure rate is reduced, the production cost is reduced, the labor intensity of maintenance personnel is reduced, and the productionefficiency and safety are improved.