Abstract: 516 clinical cases of dogs from x pet clinic in Hohhot in 2009 were analyzed in the article. The results showed that the number of death was 38,the positive rate of canine distemper （CD） attained 79.8 % by detection its antibody titer among these decease cases. It indicated that canine distemper is one of the main infectious diseases causing the death of canine. The further investigations showed conjunctivitis,respiratory inflammation,digestive functional disorder and neurological symptom are principal clinical character of CDV,it was easily caused by unscientific feeding and management.