The utility model discloses a device for testing the solubility of weakly acidic gas in alkaline absorption liquid and belongs to the field of gas absorption and separation, petrochemical industry and the like. The device is applicable to determination of the equilibrium solubility curve of the weakly acidic gas under different gas partial pressures and at different temperatures. The device consists of a gas delivery system, a reaction tank, a temperature control system, a sampling system, a gas partial pressure measurement system, a liquid sample analysis system and a gas volume measurement system. According to the reaction tank made of stainless steel, the measurement range of gas partial pressure is expanded, the temperature of gas and liquid is controlled respectively to be uniform, and a magnetic stirrer can be used; an intelligent instrument is used for high-accuracy temperature control and pressure display; a liquid sample is analyzed by using an acidolysis method to obtain the solubility; the liquid remained in a pipeline in the last experiment is blown by the gas so as to improve the accuracy; by using a gas measuring pipe as a gas volume measurement tool, the accuracy of gas volume measurement is ensured, so that an experiment result is stable and reliable. The device is stable and reliable in test performance, simple and convenient.