Background: FLT3-internal tandem duplication mutations (ITDs) are found in approximately 30% of patients with acute myeloid leukemia (AML) and are markers of poor prognosis. However, the characteristics of FLT3/ITDs in Chinese AML patients have rarely been reported. The aim of this study was to analyze the frequency and characteristics of FLT3/ITDs in Chinese AML patients. Methods: In the selected 152 cases of Chinese AML patients, capillary electrophoresis (CE) was used to analyze the frequency and characteristics of FLT3/ITDs. Next-generation sequencing was used to analyze the sequences of FLT3/ITDs positive patients. The differences of clinical features between FLT3/ITD positive group and FLT3/ITD negative group were estimated by statistical analysis. Results: 42 cases (27.6%) were FLT3/ITDs-positive, in which 34 cases (81%) had a single duplication, and the remaining 8 cases (19%) had 2 or more ITDs. Median ITD size was 42 bp and median ITD allelic ratio was 0.25. Using next-generation sequencing, ITDs integrating in non-juxtamembrane (JM) domains were detected in 12 ITDs (24%) and in JM domains were detected in 38 ITDs (76%). Furthermore, duplication of at least one residue between Y591 and Y599 was detected in 48 (96%) of all 50 ITDs, and the insertion site was strongly correlated with ITD size: more C-terminal located inserted fragments were significantly longer. Conclusions: Our data provide further evidence of the heterogeneity of FLT3/ITDs among different subgroups in Chinese AML patients. ITDs varied widely, but hotspots were concentrated. These results also suggest that next generation sequencing is a useful method for detection of FLT3/ITDs sequences.