Allergic rhinitis (AR) is a common Ig-E mediated disease of nasal mucosa, induced by an immunoglobulin E (IgE)-mediated reaction in the allergen-sensitized subjects, affecting 10% to 40% of the world population. AR could be divided into two kinds, perennial AR and seasonal AR (SAR). Allergen specific immunotherapy (AIT) is the only etiological treatment available for AR. Traditionally, AIT is divided into 2 types, subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT), both of which are effective and safe alternatives. The trial is a randomized, double-blind, placebo-controlled trial. 72 eligible SAR patients, who were sensitized to sweet sagewort (artemisia annua), were enrolled into the trial, followed by either a 32-week SLIT schedule, where the maintenance dose would be reached within 5 weeks, or placebo SLIT schedule. Standardized depot preparations of sweet sagewort (artemisia annua) extract (Zhejiang Wolwo Bio-pharmaceutical Co., Ltd., China ) were administered by means of sublingual drops.