Objective To search for the relationship between the time before diagnosis and clinic in children'sacute Leukemia. Design Clinical cases analysis. Patients 72 Child patients with acute leukemia, 39 male and 33 female. The range of age is from6 months to 15 years old. First treated patients are 44 and the second treated patients are 28. Rebults and Conclusions The average time before diagnosis (19. 14wk) in children's acute leukemiaof10 years old group(6.94wk), The diagnosis time of infiltration symptom(10.30wk) is the longest and hemorrhage symptem isthe shortest among all the symptom of first break out. The time before diagnosis have not significantdifference among all the types of ALL. The time before diagnosis of ANLL (5.24wk) is shorter thanthat of ALL (7.74wk).