With the aim to solve the contradiction between ventilation and heat preservation of confined livestock and poultry house in cold winter in northern cold region, an energy-efficiency dehumidification system, taking fin-tube heat exchanger as the core part was designed based on the principle of condensation dehumidification by using the climate characteristics of big temperature difference between indoor and outdoor. The natural-cooling refrigerant was applied circularly by this system to reduce the water vapor quality of indoor high-humidity air with internal circulation, which could avoid sending indoor air to outdoor directly or indirectly to decrease heat loss. Dehumidification rate (DR) was calculated by theory of wet air to verify the performance of dehumidification system in a confined experimental cabin. The results showed that there were four important influence factors on dehumidification and energy consumption, i.e., efficiency area of fin-tube heat exchanger, initial temperature differences between indoor and outdoor, flow rate of air and refrigerant. Indoor temperature drop was 4.67℃ and mean DR was about 2.69kg/h when average initial temperature was about 33℃ and air flow rate was 1m/s in the 36m3 closed chamber. The quality ratio of air and refrigerant flow were 0.31, 0.63 and 0.95, and the average coefficient of performance (COP) were 5.63, 12.25 and 11.03, respectively. The experimental results indicated that there would be an upper limit of the quality ratio enhancing the heat transfer. COP could not improve along with air flow rate, and this provided an advice for optimal energy consumption of humidifier. It was shown that this energy-saving dehumidification system can take full advantage of the low temperature in the northern cold region, and the dehumidification rate and energy-saving effect were obvious, which provided an efficient solution of the contradiction between environmental dehumidification and thermal insulation of livestock and poultry houses in winter of the northern cold region.