Abstract: Ketosis is a common nutrition metabolic disease of dairy cows. Using ketone powder, urine analysis strip, milk analysis strip, kit detected the ketone concentration in milk and serum of dairy cows respectively, serum β-hydroxybutyrate 1200μmol/L as the threshold for normal cows and subclinical ketosis. Urine analysis strip and milk analysis strip diagnosis standard were 200μmol/L and 5mg/dl respectively. Serum β-hydroxybutyrate and glucose concentration of healthy cows were 726±43μmol/L, 3.42±0.05mmol/L respectively, subclinical ketosis cows were 2563±238μmol/L, 2.78±0.07mmol/L, difference was significant（P<0.05）. Sensitivity and specificity of milk analysis strip were 67% and 92%, urine analysis strip were 57% and 85%，ketone powder were 60% and 94% respectively. It was an effectual method that cowside test diagnose the dairy cows subclinical ketosis with milk analysis strip.