Ovine theileriosis is a giardiasis caused by protozoan of the Taylor Genus，Taylor Family，with the invasion of the reticuloendothelial system and red blood cells of cattle，sheep，camel and other wild animals as the main feature. Ovine theileriosis was investigated in Manping Town of Minhe County，Qinghai Province. The infestation ratio of parasitized red blood cells was between 1‰~5‰，with an average of 3.2‰. There were purple pomegranate bodies in the smears of lymph node needle biopsies. The preventive trial showed that the 2 kinds of drugs such as Ivermectin and Miticide，to prevent trials，which showed that the 2 drugs could reduce the occurrence of Ovine theileriosis，and the effect of Ivermectin Injection was better than the Miticide.