Abstract: In order to study the back suction phenomenon of the freezing core technology in the determination of coal seam gas content, the self-developed gas-containing freezing response device was tested and analyzed. We carried out experiments on the back suction phenomenon during freezing and coring under different gas pressures（1 MPa, 2 MPa, 3 MPa, 4 MPa） and different degrees of metamorphism（long flame coal, coking coal, lean coal, anthracite）. The results showed that under the same conditions, with the increase of coal core gas pressure, the back suction volume of coal core gradually decreases. The back suction volume of coal core with low gas pressure（1 MPa, 2 MPa） is far greater than that of high gas pressure（3 MPa, 4 MPa）. The suction speed gradually decreases with the decrease of coal core temperature, and the suction duration gradually decreases with the increase of gas pressure. The influence trend of metamorphic degree on coal core suction is the same, showing that the higher the metamorphic degree, the longer the time of coal core suction phenomenon, and the greater the amount of coal core back suction, the longer the duration of suction with the increase of metamorphic degree, and the lower the speed of suction with the decrease of coal core temperature.