The invention discloses a multifunctional full-automatic liquid adding and discharging device for a pathological section dyeing machine, which comprises a liquid inlet and outlet pipeline, a dyeing tank busbar, a reagent liquid path control busbar, a pump, a waste discharge confluence pipeline, an overflow pipeline, an air pressure adjusting mechanism, a pipeline cleaning mechanism, a pressure detection module and a concentration detection module. The liquid inlet and outlet pipeline is communicated with each dyeing tank, one end of the dyeing tank busbar is connected with the liquid inlet and outlet pipeline, the other end of the dyeing tank busbar is connected with the reagent liquid path control busbar through a pump, and the reagent liquid path control busbar is provided with a plurality of reagent liquid path liquid inlet and outlet pipes.The reagents do not need to be manually replaced, the labor intensity is reduced, the operation safety (including biological safety and inflammable and explosive material management safety) is improved, reagents can be recycled, the stability of the reagents is guaranteed, the liquid adding speed is high, liquid discharging is more thorough, and meanwhile the functions of waste discharging, overflow prevention, pipeline and dyeing tank cleaning and pipeline pressure and reagent concentration detection are achieved.