The paper aimed to study the mechanism of 2009 influenza type A H1N1 (A/H1N1/2009) by detecting the levels of serum cytokines in patients with influenza A/H1N1/2009 before and after oseltamivir treatment. Twebty healthy volinteers were selected as control and 30 patients with influenza A/H1N1/2009 were divided into before oseltamivir treatment group (BTG) and after oseltamivir treatment group (ATG). The enzyme-linked immunosorbent assay was used to detect the levels of interleukin 10 (IL-10), IL-2, IL-8 and interferon γ (IFN-γ) in serum. The results were shown as follows. The serum levels of IL-10, IL-2, IL-8 and IFN-γ in BTG were significantly higher than those in the control group (P<0.05). Compared with those in the contol group, the serum levels of IL-10, IL-2 and IL-8 in ATG were also significantly higher (P<0.05), while the level of IFN-γ was not significant (P>0.05). The levels of IL-10 did not change significantly between BTG and ATG (P>0.05). Compared with those in BTG, the levels of IL-2 and IFN-γ in ATG were significantly decreased（P<0.05）, however the level of IL-8 was significantly higher （P<0.05）. The results suggest that IL-10, IL-2, IL-8 and IFN-γ may be related with the pathogenesis of A/H1N1/2009 influenza; IL-2, IL-8 and IFN-γ may be involved in antiviral mechanism of oseltamivir.