The invention discloses a physicochemical comprehensive treatment system for a dangerous waste liquid. The system comprises a waste liquid storage tank, a paper tape filter, a quenching and tempering groove, four reagent grooves, three reaction vessels with stirrers, a tail gas absorption groove, a buffer tank, a water injection vacuum set, a centrifuge, a suction filtration groove, a membrane processor, a filter press, a filtrate collection pool, two waste liquid intermediate grooves, a sludge collection pool and a wastewater regulating pool. Each processing unit of the invention can be switched and combined flexibly so as to be adapted to various physicochemical comprehensive treatments of a dangerous waste liquid, such as acid-base neutralization, coagulation sedimentation, redox, desalination, solid-liquid separating and tail gas purifying treatment etc. Under the condition of satisfying the technical requirements of waste liquid treatment, the system of the invention can reduce repeated treatment facility construction and investment. Under the premise of ensuring a good treatment effect, the system provided in the invention reduces human consumption, material consumption and energy consumption, and reduces the treatment operation cost of per unit of waste amount. The escaping and leaking phenomena common in present waste liquid treatment processes can be avoided, and secondary pollution to the environment as well as damage to people can be eradicated.