Abstract: Summarize the historical evolution of the connotation of "two infected with cold pathogen" in The Yellow Emperor's Inner Classic, and propose that the "two infected with cold pathogen" in The Yellow Emperor's Inner Classic is the condition where Taiyang and Shaoyin meridians simultaneously infect cold pathogen when Shaoyin is deficient. This belongs to a critical syndrome, and is significantly different from the "two infected with pathogen" syndromes of Taiyang and Shaoyin meridians proposed in Treatise on Cold Damage. The "two infected with pathogen" in Treatise on Cold Damage has narrow meaning and broad meaning. The narrow meaning specifically refers to the infection of pathogen in both the external and internal meridians; while the broad meaning proposes that despite how the disease occurs and spreads, as long as the two meridians are infected with pathogen, it belongs to the category of "two infected with pathogen". The broad meaning not only involves complex diseases of both the external and internal meridians, but also includes related contents of complex and combination diseases of other two meridians, and even the same meridian-mediated meridian-organ diseases. Referring to the treatment of "two infected with pathogen" in Treatise on Cold Damage, it is proposed that the "two infected with cold pathogen" in The Yellow Emperor's Inner Classic can be first treated with Sini decoction or Tongmai Sini decoction for the interior, and then decide whether to use Guizhi decoction, etc, to relieve external symptoms based on the condition.