In this paper, canonical ensemble theory is applied to investigate the second virial coefficient of a classical mixed gas and the limitative expression of the second virial coefficient formula is discussed; in the meantime, the application of the investigation conclusion is put out 摘要本文應(yīng)用正則系綜理論研究了經(jīng)典混合氣體的第二維里系數(shù),并討論了各種極限情況,同時指出了所得結(jié)果的實際應(yīng)用。