Abstract: Objective To make certain whether natural plague focus exists in Deqin county, Yunnan province and provide evidence for the prevention and control of plague. Methods Field survey and laboratory detection were conducted in Deqin from June to July 2012. Specimens were collected to detect plague F1 antigen and antibody by using indirect hemagglutination test (IHA), enzyme-linked immunosorbent assay (ELISA) and colloidal gold immunochromatography assay (GICA) and to isolate Yersinia pestis. Results No Yersinia pestis and F1 antigen were detected in 9 marmot specimens collected. Totally 174 dog serum samples, 9 marmot serum samples, 23 rat serum samples and 853 rat heart infusion samples were used to detect plague F1 antibody. And 2 dog serum samples were positive in IHA, 16 dog serum samples were positive in ELISA and 3 dog serum samples were positive in GICA. Two dog serum samples were positive in all the 3 tests and Western blotting confirmed they had specific chromogenic reaction with plague F1 antigen. Conclusion Plague F1 antibody was detected in dog serums in Deqin, but further study is needed to confirm whether natural plague focus exists in Deqin.