Abstract: In a sheep farm in Zhoukou City, Henan Province, sheep showed symptoms of inability to ruminate, shortness of breath and enlargement of abdominal circumference, and the mortality rate was as high as 10%. In order to find out the cause of the disease, in this experiment, the disease investigation, dissection, blood biochemical index determination, smear and histopathological examination were used for the diagnosis and analysis of the diseased sheep. The results showed that the sheep in this farm were only fed concentrate feed within one week before the onset of disease, and the roughage was not supplemented, and the feed ratio was unreasonable. Autopsy showed right heart hypertrophy and a full, enlarged gallbladder; black patches on the surface of the liver; blood stasis appeared in the lung; the kidneys were yellowish and enlarged; rumen and intestinal mucosa showed edema, with watery contents. The concentration of lactic acid in the blood was much higher than the reference value, with decreased calcium ion concentration and electrolyte imbalance, which showed the characteristics of acidosis. No pathogenic microorganisms were found on blood smears and tissue smears. Histopathological changes were mainly manifested as hepatic atrophy necrosis, subacute glomerulonephritis, and interstitial pneumonia, which were consistent with the pathological characteristics of acidosis. The results suggested that the cause of the disease of sheep in the farm was acidosis.