Objective To explore the diagnostic value of magnetic resonance diffusion-weighted imaging (DWI) for meningiomas of different grades, providing imaging evidence for preoperative assessment and grading of meningiomas. Methods A retrospective analysis was conducted on the clinical and imaging data of 80 patients with meningiomas who underwent surgical treatment and were pathologically confirmed in The First Affiliated Hospital of USTC (Anhui Provincial Hospital) from April 2020 to February 2024. According to the 2016 WHO classification of central nervous system tumors, patients were divided into a low-grade group (WHO grade Ⅰ, 40 cases) and a high-grade group (WHO grades Ⅱ and Ⅲ, 40 cases). All patients underwent 3.0T MRI scans within one week before surgery, including conventional sequences and DWI sequences. The mean apparent diffusion coefficient (ADCmean), minimum apparent diffusion coefficient (ADCmin), and ADC values of the contralateral white matter were measured. Independent sample t-tests were used to compare differences between the two groups, and ROC curve analysis was performed to evaluate the diagnostic efficiency of each ADC parameter for meningioma grading. Results ① Significant differences were found in ADCmean, ADCmin, and contralateral white matter ADC values between the low-grade and high-grade groups (P ＜ 0.05). The low-grade group had higher ADCmean, ADCmin, and contralateral white matter ADC values than the high-grade group(t=2.037, 2.586, 2.795；P=0.045, 0.012, 0.007). ② ROC curve analysis showed that the area under the curve (AUC) for ADCmean, ADCmin, contralateral white matter ADC, and their combined predictive factors were 0.637, 0.659, 0.690, and 0.767, respectively, all demonstrating certain diagnostic value (P ＜ 0.05). ③ The combined predictive factor showed the best diagnostic efficiency, with a specificity of 0.850, a Youden index of 0.425, and a cutoff value of 3.299. The contralateral white matter ADC demonstrated the best sensitivity, at 0.650. Conclusions Magnetic resonance diffusion-weighted imaging has significant diagnostic value for preoperative grading of meningiomas. ADCmean, ADCmin, and contralateral white matter ADC values can serve as imaging indicators to differentiate between low-grade and high-grade meningiomas. The combined application of these parameters can improve diagnostic accuracy and provide important references for developing individualized treatment plans.