The present invention provides a method and system for continuously producing 2,5-dichlorophenol. The method comprises an aniline salt diazotization process and a diazo solution hydrolysis process. The aniline salt diazotization process comprises the steps of continuously feeding aniline salt and nitrite into a diazo intensive mixing apparatus; performing a diazotization reaction under intensive mixing; feeding a diazo solution generated by the reaction into a diazo solution storing tank; back-mixing a part of the diazo solution in the diazo solution storing tank after cooling and feeding the part of the diazo solution into the diazo intensive mixing apparatus; removing all or a part of heat generated in the diazotization reaction by using the back-mixed cryogenic diazo solution; and directly performing continuous hydrolysis on the other part of the diazo solution. According to the method provided by the present invention, by adopting an intensive mixing process and a back-mixing process, mass and heat transfer during the diazotization reaction and the hydrolysis reaction can be quickly performed; heat can be taken away or given in time; a reaction time is shortened; the side reaction is reduced; the heat utilization rate is improved; the costs are lowered; and a safety factor and the device production capacity are improved.