The design and construction of the BES main drift chamber

The main drift chamber of the Beijing Spectrometer (BES) has been described briefly, including its physical design, mechanical design and construction, choice of the working gas as well as prototyping. The performances of the chamber, experimental or expected, have been given: solid angle coverage, gain and efficiency, spatial resolution on the R-υ plane, axial spatial resolution, dE/dx energy resolution and particle identification power, etc