Coal has been widely used in many aspects in northern China. Nevertheless, urgent environmental protection has been required to prohibit the coal combustion for the heating source in winter since 2017. The application of clean energy has been the key issue need to be solved in recent years, particularly on the energy consumption of buildings. Air source heat pump (ASHP) as a piece of clean energy equipment has widely been used in civil and industrial buildings. But there is no application of ASHP in swine houses. It is an urgent need to conserve energy and reduce pollution emissions. In this study, an investigation of ASHP was carried out in the swine houses of Shunyi District, Beijing. The experimental size of the swine houses was 42 m long and 9.3 m wide. The ASHP heating system was installed in a swine barn. There were 6 pipes to supply water, and other 6 pipes to return water for the heating floor. The monitoring period was selected for the equipment performance: November 20th, 2016-April 16th, 2017. The first stage (January 3rd, 2017-January 8th, 2017): swine houses with pig test (two units). The second stage (January 9th, 2017-January 20th, 2017): swine houses with no pig test. The energy-saving rate of ASHP and direct electric heating systems were compared to measure the Coefficient of Performance (COP). ASHP, direct electric heating, Liquefied Natural Gas (LNG), and natural gas heating were compared by the unit energy operating price. The average supply water and return water temperature of ASHP was also measured. The results showed that the COP of the ASHP system was 2.86 when the average outdoor temperature was 0.1 ℃ during the heating period. The energy-saving rate of ASHP was 66%, compared with direct electric heating. The unit energy operating prices of ASHP, LNG, Natural Gas, direct electric, and ASHP were 0.62, 0.34, 0.37, and 0.64 yuan/ kW•h, respectively. The CO2 emission was reduced by 8 636 kg during the experiment. The average supply water temperature and return water temperature of ASHP were (37.6±2.4) and (34.9±2.2) ℃, respectively. ASHP heating system presented the potential to reduce energy consumption and CO2 emission, serving as an economical and clean alternative energy source for pig barns heating. Consequently, the air source heat pump system is suitable for swine houses with solid floors, but not with fully slatted floors.