Objective To study the influence of FLT3 gene mutation on acute myeloid leukemia(AML). Methods We used PCR combined with direct sequencing and cloning sequencing to investigate FLT3 mutation in 50 AML patients, and further analyzed clinical data of these patients. Results FLT3-ITD mutation was found in 20% AML patients with normal karyotype, which was higher than that in patients with abnormal karyotype. Compared with wild-type group, the WBC count, hemoglobin and blast cells in bone marrow were all high in FLT3-ITD positive group which with lower CR ratio. Conclusions FLT3 mutation is the major molecular marker of AML patients with normal karyotype, which is very important for prognosis analysis and targeted therapy of AML.