Abstract: Objective To study the changes of hematological system parameters in allergic asthma model of rats. Methods Twenty healthy male Wistar rats were randomly divided into normal control group and asthma model group. Rats in asthma model group were sensitized 3 times with ovalbumin (OVA) and aluminum hydroxide gel and challenged with OVA once, and those in normal control group were sensitized with 0.9% normal saline. Changes of hematological system parameters in the rats were assessed according to their hemorheology, blood gas and blood coagulation. Results The plasma and whole blood viscosity and FIB level were significantly higher, the PaO₂ and SaO₂ were significantly lower, the PT and TT were significantly longer in asthma model group than in normal control group (P＜ 0.01, P＜ 0.05). Conclusion Parameters of blood coagulation and blood gas are changed in allergic asthma model of rats.