Objective：To explore the value of axial iterative decomposition of water and fat with echo asymmetrical and least - squares estimation quantitation sequence（IDEAL-IQ）combined with intravoxel incoherent motion（IVIM）quantitative parameters in assessing the risk stratification of acute B lymphoblastic leukemia（B - ALL）children and predicting their early response to chemotherapy. Methods：A total of 84 children with B-ALL were enrolled. According to the WHO risk classification，the children were divided into the low - risk group（n=5），the medium - risk group（n=61），and the high - risk group（n=18）. Among them，79 children underwent chemotherapy and received lumbar IDEAL - IQ and IVIM scans before chemotherapy and on day 36 of induction chemotherapy. According to day 33 bone marrow MRD after chemotherapy，the children were divided into a CR group（54 cases）and an N -CR group（25 cases）. Clinical data such as age，sex，risk stratification，peripheral blood white blood cell count（WBC），bone marrow blast percentage，lactate dehydrogenase（LDH），and central nervous system leukemia（CNSL）involvement were also collected. Results：In evaluating the risk stratification of children with B -ALL，the f value of the lumbar vertebrae in the high - risk group was significantly higher than that in the medium -and low - risk groups（all P ＜ 0.001）. Logistic regression analysis with peripheral blood WBC and lumbar vertebral f value as independent variables and clinical risk as the dependent variable revealed that f value is a highrisk factor for B-ALL（ORf=48 082.101，P ＜ 0.001）. In evaluating the early chemotherapy response，compared to the N-CR group，the CR group had significantly higher proton density fat fraction（PDFF）and effective transverse relaxivity rate（R2* ）after chemotherapy （P=0.005，P=0.008）. Pretreatment risk stratification，pure diffusion coefficient（D），and pseudo diffusion coefficient（D* ）values differed significantly between the CR and N - CR groups（P ＜ 0.001，P=0.024，and P=0.030）. Post - chemotherapy PDFF，pre - chemotherapy D ，and D* values were independent risk factors for N-CR. The values of the pre-chemotherapy D+D* in predicting N-CR had an area under the curve（AUC）of 0.817，slightly higher than that of the post-chemotherapy PDFF（AUC=0.807）. Conclusion：The f value of the lumbar vertebrae can be used to predict the clinical risk stratification of children with B-ALL. The pre-chemotherapy D+ D* value has significant predictive value for the early chemotherapy response of children with B-ALL.