Interferon (IFN)α is an effective drug against the treatment of HBV and HCV, including regular IFNα, complex IFN and pegylated interferon α (PEG-IFNα). PEG-IFNα is used in combination with ribavirin as a standard treatment regimen against HCV. The course of HBV or HCV treatment with IFN takes about 1 year, and may take longer in some special patients. How to predict the antiviral effect of interferon in advance? Which populations are more effective with interferon anti-HBV or HCV treatment? For this reason, we need to understand the common factors affecting the efficacy of interferon in order to facilitate a more rational application of interferon for antiviral therapy. It has been studied that the factors affecting the efficacy of interferon (IFN) alpha anti-HBV are different from anti-HCV and should be distinguished. Interferon (IFN)α anti-HBV therapy often has better efficacy when the following factors are present: 1, high ALT level before treatment; 2, HBV DNA <2×108 copies/ml [<4×107IU/ml]; 3, female; 4, short duration of disease; 5, non-maternal-to-child transmission; 6, heavy inflammatory necrosis of liver tissue and light fibrosis; 7, good compliance with treatment; 8, no HCV, HDV or human immunodeficiency virus (HIV) co-infection; 9, HBV genotype A; 10, serum HBV DNA undetectable at 12 or 24 weeks of treatment. Among them, pre-treatment ALT, HBV DNA levels and HBV genotype are important factors in predicting the efficacy. Some findings suggest that quantitative detection of HBsAg level or HBeAg level has good predictive value for treatment response during PegIFNα-2a treatment. Interferon (IFN)α anti-HCV therapy tends to be more effective in those with the following factors: 1, HCV genotype 2 or 3; 2, viral level <2×106 copies/ml; 3, age <40 years; 4, female; 5, short duration of HCV infection; 6, mild liver fibrosis; 7, good compliance with treatment; 8, no significant obesity; 9, no co-infection with HBV and HIV 10.Treatment method: PEG-IFNα combined with ribavirin is the best.