The invention discloses a continuous observation system for dissolving of methane in a surface water body, relating to greenhouse gas monitoring equipment. The continuous observation system is provided with a surface water pump, filtering equipment, temperature and salinity measurement equipment, a flow controller, a water-vapor balance device, a temperature probe, a gas pump, a cold trap, a waterproof electrode, a filtering device, an off-axis integral cavity output spectrum detector, a valve and a standard gas cylinder; a water inlet of the surface water pump is arranged underwater, a water outlet of the surface water pump is connected with an inlet of the filtering equipment, an outlet of the filtering equipment is connected with the temperature and salinity measurement equipment, an outlet of the temperature and salinity measurement equipment is connected with an inlet of the flow controller, an outlet of the flow controller is connected with the balance device which is communicated with the atmosphere, an air outlet formed in the upper part of the balance device is connected with a gas inlet of the gas pump, the temperature probe is arranged in the balance device, a gas outlet of the gas pump is connected with an inlet of the cold trap, an outlet of the cold trap is connected with the waterproof electrode, an outlet of the waterproof electrode is connected with an inlet of the filtering device, an outlet of the filtering device is connected with an inlet of the detector, and an outlet of the standard gas cylinder is connected with the balance device and the detector through the valve respectively.