Abstract: 41 lambs of Tibetan Sheep were purchased from Cuomei County of Shannan Prefecture in Tibet. The diarrhea of lambs that defecated watery putrid dark stools occurred after they arrived at Lhasa one day. Some lambs defecated the bloody stools or even died. The mixed infection of Escherichia coli and coccidian was confirmed by clinical diagnosis,postmortem and lab examination. The drug sensitivity results of E. coli isolated and cultured showed that E. coli was sensitive to gentamicin, amikacin, cephalosporinⅤand ceftazidime. Taking antisepsis and anti-inflammation, supplementing body fluid, preventing the electrolyte disorder and self acidosis and anti-shock as the treatment principles, a series of comprehensive measures were taken, and the diseased lambs were healed after 2 weeks.