The invention discloses a system for cooling carbon dioxide by low-pressure ammonium carbamate condenser circulating water. The system comprises a circulating water pipeline for circulation of the circulating water, a circulating water pump is arranged on the circulating water pipeline, a water temperature regulating system and a high-temperature carbon dioxide cooling system are serially connected, arranged on the circulating water pipeline and circulated by the circulating water pump, the water temperature regulating system comprises a temperature control valve, a circulating water cooler and a flow control valve which are serially connected by the circulating water pipeline, the flow control valve is parallelly connected with the temperature control valve and the circulating water cooler, the temperature control valve is positioned at a water inlet end of the circulating water cooler, the high-temperature carbon dioxide cooling system comprises a low-pressure ammonium carbamate condenser and a carbon dioxide cooler which are parallelly connected, a gas feeding end of the carbon dioxide cooler is communicated with a carbon dioxide dehydrogenation reactor, and a gas discharging end of the carbon dioxide cooler is communicated with a urea synthesis device.