Study the effection of substance P(SP) on Eotaxin in allergic rhinitis(AR) through SD rats. An AR model with SD rats was established by using ovalbumin then divided into four groups, one were continue sensitized by ovalbumin, and the second group were treated with treated with substance P (SP) as induction group, the third group were treated with substance P antagonist (SPA) as suppression group,and the others were treated with saline for control. The sneezing and nose rubbing and leukocyte infiltration of nasal lavage,IgE in blood serum,CO concentrations in plasma were recorded,then the expression of Eotaxin in nasal mucosa were determinated by real time RT-PCR and immunohistochemical, and Eotaxin level in serum and nasal lavage fluid were also detected by ELISA. The expression of Eotaxin and level of Eotaxin in serum and nasal lavage fluid of sensitized group were higher than those of control(P<0.01), and all these items were show higher when treated with SP and lower as treated with SPA(P<0.05). SP plays a significant role in the pathogenesis of AR through effection on Eotaxin, and the level of Eotaxin positive correlate with the level of SP.