Abstract: The JEFRI?PVT apparatus from DBR Company of Canada was used to test the phase transition from well bottom to well head and the physical parameters of high CO2 ? bearing natural gas, such as compressibility factor (Z?factor), formation volume factor (FVF), compressibility, and density. The experimental results show that no phase transition can be defined at experimental ranges, and with pressure rising, the Z?factor decreases and then increase(the minimal value appears at about 15 MPa), the density rises and both FVF and compressibility decrease (the decreasing amplitude at low pressure is larger than that at high pressure);with CO2 content increasing, the Z?factor decreases and the density increases (the increasing amplitude at high pressure is more obvious than that at low pressure), and both FVF and compressibility have little change; with temperature rising, the Z?factor increases (the biggest change arrives at about 15 MPa), the FVF rises(the increasing amplitude at low pressure is more obvious than that at high pressure), the density decreases (the decreasing amplitude at high pressure is more obvious than that at low pressure), and compressibility has little change