Objective To explore the therapeutic effect and safety of sublingual allergen specific immunotherapy (SLIT) for the treatment of bronchial asthma with allergic rhinitis. Methods One hundred and twenty children from 5 to 14 years old with asthma and allergic rhinitis were selected and randomly divided into the SLIT treatment group (sublingual administration of the dermatophagoides farinae drop) and conventional treatment group. Each group had 60 patients. Scores of asthma control questionnaire (ACQ), rhinitis symptoms, monthly medication and adverse reactions were recorded. The specific IgE (SIgE) value of serum dermatophagoides farinae was measured. Results After treatment for one year, the scores of ACQ, rhinitis symptom, and monthly asthmatic medicine and the SIgE value of serum dermatophagoides farinae of the SLIT treatment group and conventional treatment group were decreased. The decrease of the SLIT treatment group was significantly more than that of the conventional treatment group. The differences were statistically significant (P<0.01). The incidence of side effects (including skin rash, nasopharyngeal itch, and asthma attack) relevant to immunotherapy was 13.3% and no serious side effects happened. Conclusion SLIT can safely and effectively treat children with bronchial asthma and allergic rhinitis and is better than the conventional therapy.