The invention relates to an absorption air conditioner cooling water main frame and a method of anti-freezing pipe thereof. The absorption air conditioner cooling water main frame comprises a high-voltage generator (1), a condenser (2), a low-voltage generator (3), an absorber (3), an evaporator (5), a high-temperature heat exchanger (6), a low-temperature heat exchanger (7), a solution pump (8),a cryogenic fluid pump (9), a heat input device (10), a water pump of chilled water (15), a chilled water flow capacity protecting sensor (16) and a main frame central process unit (17), a connectingpipe between the condenser and the evaporator is provided with a solenoid valve, pipeline connecting an chilled water inlet port of the evaporator with the water pump of chilled water is equipped witha solenoid valve. When power source is cut off or accidents that a chilled water recycling pump stops from working and the like or faulty operation occurs, a condenser liquid coolant by-pass solenoidvalve is opened, or a chilled water drainage solenoid valve is opened, thereby avoiding evaporator freezing pipe of the absorption air conditioner cooling water main frame from accidents. The absorption air conditioner cooling water main frame is reasonably designed, and the method of anti-freezing pipe thereof is simple in operation, convenient and practical.