Abstract: With the importance of environmental protection, “2+26” cities in China have been banned from coal heating, and pig farms urgently need to find a low-cost heating way of energy saving and emission reduction. Air source heat pump is a kind of energy saving device by inputting a small amount of highgrade energy (electric energy) to achieve the goal that the heat flows from low-grade thermal energy (air) to high -grade thermal energy (such as water, oil, etc.). As a clean energy, air can be selected as a kind of heating energy but air source heat pump can also be affected by outdoor temperature and related technical factors. In order to understand heating effect of air source heat pump for floor heating of pig house, one nursery pig house in Beijing was selected to be the experimental pig house. The experimental pig house was 42 m long and 9.3 m wide and floor heating area was 42 m×5.7 m. Two air source heat pumps (5P) were installed to the heating system of the nursery pig house with floor heating, and the thermal environment indexes of the heating system were monitored and analyzed. There were 12 pipes for supply water and other 12 pipes for return water in the heating floor. The test was divided into two periods, the equipment performance monitoring period and the pig house thermal environment effect test period. Equipment performance monitoring period: November 20th, 2016-April 16th, 2017. The pig house thermal environment effect test period was divided into two stages. The first stage (January 3rd, 2017-January 8th, 2017): pig house with pig test (two units). The second stage (January 9th, 2017-January 20th, 2017): pig house with no pig test (empty pig unit - unit 2). The results showed that the outdoor minimum and maximum temperatures were -11.0 and 12.1 ℃ during the test period, respectively. In the floor heating pig house, there was a positive linear correlation between the ground temperature and the supply water temperature, the correlation between the ground temperature and the outdoor temperature also indicated a positive linear correlation. However, the correlation between the ground temperature and the heating distance showed a negative correlation. When the actual system supply water temperature was 32.5-41.2 ℃, the 0.3 m height temperature range in the pig house of two units with pigs at measuring point P3 and measuring point P6 (the two measuring points were in the middle of the pig house) was 19.4-21.5 ℃. When the actual system supply water temperature was 30.0-41.0 ℃, the ground temperature range at measuring point T1 (the nearest measuring points to the water distributor, 24 m of distance from the water distributor) and measuring point T6 (the farthest measuring points to the water distributor, 60 m of distance from the water distributor) in the pig house without pigs was 19.1-28.6 ℃. The actual system water supply temperature was 1.8-4.0 ℃ lower than the setting temperature during the test period. During experimental period of stage 2, the ground temperature at measuring point T1 in Unit 2 in the pig house without pigs was lower than the actual supply water temperature by 8.3-13.1 ℃, and the ground temperature of measuring point T6 decreased by 0.5-1.8 ℃ compared with the ground temperature of measuring point T1 and the difference between the two measuring points was 36 m. Moreover, the average temperature at 0.3 m height decreased by 5.0 ℃ compared with the average ground temperature, but there was no obvious change in temperature at different heights above 0.3 m. As for Beijing, the average outdoor temperature was 0.1 ℃ in heating period, the recommended setting temperature and actual supply water temperature for nursery pig house should be 43-32 ℃ and 40.6-29.9 ℃, respectively. The air source heat pump heating system was suitable for the nursery pig houses with floor heating system in Beijing.