The utility model relates to a high-pressure reaction unit, in particular to a high-pressure reaction kettle device in which liquid chemically reacts. The technical problems that the conventional high-pressure reaction kettle can only react in a closed system generally, and cannot meet requirements of a high-temperature and high-pressure reaction system in which gas is required to be fed continuously, simultaneously, tail gas is required to be discharged continuously, and liquid chemically reacts are solved. According to the technical scheme, a cooling return pipeline is arranged on the upper part of the outside of a high-pressure reaction kettle, so that a large quantity of gas generated in a reaction process is condensed to form a back flow, and the back flow enters the reaction kettle again to continuing reacting. In the cooling return pipeline, a gas downward-flowing pipeline (10), a condenser (14) and a feed/return three-way pipe (18) are sequentially connected with one another, and a gas flow direction and a condensed liquid flowing direction are vertically downward, so that condensed liquid easily returns to the reaction kettle to continue reacting. The cooling return pipeline with the structure is good in cooling effect, the reaction conversion rate is increased, and the cost is saved.