ObjectiveTo assess therapeutic effect of extract of Polygonum paleaceum Wall（PPW） on influenza A H1N1 virus infection in Balb/c mice. MethodsMice model of influenza A H1N1 virus infection was established by intranasal method, different doses of PPW were given by gavage, positive control group was given oseltamivir, and mice without giving oseltamivir were in virus control group. Life status of mice within 14 days was observed, lung index of mice was calculated, relative amount of viral nucleic acid and virus titer in lung tissue were detected. ResultsThe median lethal dose of influenza A H1N1 virus to mice was 10-6. Survival rates of mice in positive control group, high PPW dose group, and middle PPW dose group were all 100%, the average survival time was 14 days, survival rate and average survival time of mice in low PPW dose group were 42.86% and 9.14 days respectively, while in virus control group were 0 and 3.57 days respectively. The average survival days of mice in different groups were statistically significant (F=8.53, P=0.02); average survival days of mice in positive control group, high PPW dose group, middle PPW dose group, and low PPW dose group were all higher than those of virus control group (P<0.05). Lung index of positive control group, high PPW dose group, middle PPW dose group, low PPW dose group, and virus control group were (0.84±0.07)%, (0.81±0.07)%, (0.84±0.10)%, (0.84±0.10)%, and (1.42±0.12)% respectively, difference was statistically significant（P=0.03）; relative amount of viral nucleic acid were 0.37±0.11, 0.42±0.06, 0.42±0.06, 0.65±0.19, and 1.00±0.06 respectively, difference was statistically significant（P=0.04）; titer of virus were 2.49±0.12, 2.35±0.29, 2.43±0.15, 2.46±0.12, and 2.80±0.16 respectively, difference was statistically significant（P=0.04）. Lung index, relative amount of influenza virus nucleic acid and virus titer in lung tissue of positive control group and different PPW dose groups were all lower than that of virus control group (P<0.05); but the above indexes in positive control group were not statistically significant compared with different PPW dose groups (P>0.05).ConclusionExtract of PPW has inhibitory effect on influenza A H1N1 virus in vivo, it can decrease lung tissue lesions and reduce the mortality of mice infected with influenza A H1N1 virus.