Abstract: The beam pipe is installed in the inner cylinder of the drift chamber (DC) which is one of the detectors of Beijing Spectrometer Ⅲ (BES Ⅲ). There will be much more heat on the inner surface of the beam pipe, which is mainly from synchrotron radiation and high order mode radiation when the new generation Beijing Electron and Positron Collider (BEPC Ⅱ) is operating. Continuous high temperature or large temperature fluctuation can cause the DC to detect particles abnormally. Therefore, the temperature field of the beam pipe was researched by means of the finite elements simulation and experiments, and the temperature of the inner wall of the DC inner cylinder was studied based on the numerical analysis. The result shows that the temperature of the cooling oil and cooling water for the central pipe and the extending pipe of the beam pipe should be set on 291.4 K and 291.6 K respectively when the radiation heat on the inner surface of the beam pipe is 0.750 W. On this condition, the inner surface temperature of the DC inner cylinder can be controlled in the range of 292.8-293.9 K, which satisfies the requirement of （293±2）K and provides guarantee for the BES Ⅲ detecting particles accurately and the BEPC Ⅱ operating normally.