Abstract: This investigation was aim to understand the prevalence of Mycoplasma ovipneumoniae (MO) in Yanbei region of Shanxi province and to provide scientific basis for disease prevention and control. 96 serum specimens of sheep or goats were selected randomly from 12 counties of Datong, Shuozhou and Xinzhou in Yanbei region. The serologic survey was conducted by indirect hemagglutination test. 37 serum samples were positive, and the average positive rate of MO was 38.54%, the highest was Xinzhou(44%), the lowest was Shuozhou(25%). The positive rate in different counties of the same city was different too,such as Datong with the highest in Hunyuan county (66.7%). Farming style, environmental sanitation, introduced quarantine, or age of animal all had effect on the development of MO. These results suggested that the positive rate of MO in Yanbei, Shanxi was relatively high, and poor ventilation and hygienic quality were the main inducing factors.

Key words: Mycoplasma ovipneumoniae; Yanbei region; serological investigation