【Abstract】Objective To better understand the acidosis of ketoacidosisonset patients. Methods 187 diabetic ketoacidosis patients were divided into ketoacidosisonset group (75 cases) and nonketoacidosisonset group (112 cases). Both groups were divided into type 1 diabetes group and type 2 diabetes group. The age, glucose，serum sodium，serum potassium，glycated hemoglobin and PH value were measured. Results The age and the level of glycated hemoglobin of Ketoacidosisonset group were lower than that in nonketoacidosisonset group. PH value of type 1 diabetes in nonketoacidosisonset group was lower than that of type 2 diabetes. The serum sodium of type 2 diabetes in Ketoacidosisonset group was normal, while the other three groups had mild hyponatremia. Conclusion We should pay attention to the seriousness of diabetic ketoacidosis caused by type 1 diabetes. The serum sodium can be used as the initial indicator of type 2 diabete，when face the Ketoacidosisonset patients.