Abstract: OBJECTIVE To evaluate the antivirus effect of Yiqing capsule. METHODS Antivirus test in vivo of Yiqing capsule was carried out by intratracheal injection of influenza A strains A/PR/8/34 (H1N1) strain in mice. The lung index, inhibition rate of lung index and death rate of mice were measured to observe the effect of anti-influenza A virus subtype H1N1 in vivo. RESULTS The 7.3 g·kg^-1 Yiqing capsule(crude) could significantly decrease the lung index of viral infected mice (P<0.05) and the mortality of 7-9?d in viral infected mice(P<0.01). CONCLUSION Yiqing capsule has good effect of anti-influenza A virus subtype H1N1 in vivo.