Abstract: Objective To research the epidemiological feature of patients infected with Encephalic arteritis complicated by leptospirosis. Methods 202 serum samples were detected by using MAT. Results Most cases occurred in spring and winter. The ratio between men and women was 1.85∶1. A concentration of cases 74.26% (150/202) occurred below 18 years old. These patients were infected by 11 serogroups of leptospirae which were Icterohaemorrhagica、Canicola、Canicola、Ballum、Autumnalis、Australis、Pomona、Grippotyphosa、Hcbdomadis、Bataviae and Manhao separately.The serogroup of Pamona was dominant as 60.89%(123/202).Conclusion These patients mostly came from poor regions in which people were used to breeding pigs in their yards.They were infected through touching the water、mud and so on contaminated by infected livestock.It was the basic measure to prevent and control the disease that doing propaganda well、improving the living condition of peasants and protecting themselves.