Objective: To explore the efficacy of olopatadine in the treatment of allergic conjunctivitis and the changes of ECP and IgE levels in the serum and tear before and after treatment. Methods:A total of 94 patients with allergic conjunctivitis were included in the study and randomized into the treatment group and the control group with 47 cases in each group. The patients in the control group were given sodium cromoglycate eye drops, while the patients in the treatment group were given olopatadine eye drops. After 2-week treatment, the clinical efficacy in the two groups was evaluated. The improvement of symptoms before and after treatment in the two groups was recorded and compared. The levels of serm and tear related indicators in the two groups were detected and compared. Results: When compared with before treatment, HA, ECP, and IgE levels in the serum and tear 1 and 2 weeks after treatment in the two groups were significantly reduced (P<0.05), and the reduced degree in the treatment group was significantly superior to that in the control group (P<0.05). Conclusions:Olopatadine in the treatment of allergic conjunctivitis can effectively reduce the serum and tear ECP and IgE levels, and rapidly alleviate the clinical symptoms of affected eye, with the clinical efficacy significantly superior to that by sodium cromoglycate eye drops.