In order to investigate the status of immunization and pathogenic infection of peste des petits ruminants（PPR）in sheep in Lijiang City of Yunnan Province，4 002 serological samples and 2 556 etiological samples were collected from 580 premises across the City during 2017 to 2020 for detection of antibodies and viral nucleic acids by ELISA and fluorescent RT-PCR respectively，then the test results were summarized and analyzed. The results showed that from 2017 to 2020，the immune qualification rate at individual level was 76.29%，and that at population level was 83.67%，both of which exceeded the minimum standard（70%）required by the Ministry of Agriculture and Rural Affairs in these years（75.33%-82.82%）except in 2020（69.23%）；the immune qualification rates at individual level were 91.20%、84.51%、76.67% and 33.40% in sheep breeding farms，commercial sheep farms，free-range households and slaughterhouses，respectively，no PPR virus nucleic acid was detected in all samples. In conclusion，PPR pathogen contamination had not been distributed across the city，and the risk of occurrence of an outbreak was low provided that no any new source was introduced；but the overall qualification rate was low and tended to decrease，especially free-range sheep and those for slaughtering that lacked of sufficient antibody protection. It was thus necessary to continue to strengthen compulsory immunization against PPR and monitoring，make efforts to supervise the introduction and transportation of sheep and improve the overall capacities for prevention and control of the disease.