The utility model relates to a deep converting system for low-pressure carboxyl reaction, in particular to a converting kettle. The system comprises a converting kettle body, and a liquid phase inlet, a liquid phase outlet, a gas phase inlet and a gas phase outlet which are arranged on the reaction kettle body, wherein, a heat exchanger is arranged in the converting kettle body, can penetrate out of the side wall of the converting kettle body, and can also be arranged in the converting kettle body. The heat exchanger adopts water circulation cooling, and is completely immersed in reaction liquid during work. The heat exchanger can adopt coil heat exchanger or a shell and tube heat exchanger. The heat exchanger and the reaction kettle body are sealed by a flange. The converting kettle realizes stable and standard temperature in the converting kettle by arranging the heat exchanger in the converting kettle, ensures the safe production, and enhances the service life of the device.