The mechanism of xylitol poisoning in dogs was studied. Eighteen adult,clinicallynormal Pekingese dogs(9/sex,3±1 years/age) with body weights(7±1kg) were fed xylitol solution.Blood samples were collected on min 0,10,20,30,40,50,60,90,120,180,240 and h 4,8,12,24,72,120,168 before and after feeding xylitol solution. The level of insulin of low dosing group(LD) andhigh dosing group(HD,P<0.01) groups rose sharply from min 20 after feeding the xylitol solution,peaking on minute 40； so the blood glucose values of them started to decrease from min 30,andreached lowest ones on min 50(P<0.01). The values of ALT(LD) and AST(HD) increaseddramatically higher(P<0.01) than that of the control groups(CO) from h 4 to 12,respectively. Thesignificant differences(P<0.01) of the activity of ALT(HD) lasted for 3 days. In contrast with that of CO,both the values of calcium iron of LD and HD were much higher on min 60(P<0.05)； however,the values of inorganic phosphorus of LD and HD were far lower(P<0.01) at the same time. Thelevels of potassium ion begun to decline on min 40,and reached the lowest ones(P<0.01)(LD,on min90； HD,on min 60). The other parameters had no significant differences between groups. This studysupplied the base data for diagnosis and treatment the xylitol poisoning in dogs.