BESS is characterized by increased cerebrospinal fluid in subarachnoid spaces; some infants with BESS were accompanied with mildly motor and language delay. White matter (WM) development is important to neurodevelopmental outcomes, but relationships between BESS and WM maturation are not very clear. This study aims to quantitative assess WM microstructures of in infant with BESS aged 4-6 months by conventional diffusion and WMTI metrics. Significant decreased FA, α and increased RD, AD, MD, RDe were found in infants with BESS. All results suggested underlying alterations of WM, especially for myelination outside axons. It may provide additional information for neurodevelopment outcomes.