<p>Scratching is one of the primary causes of internal leakage in hydraulic cylinders of construction machinery. In this study, a hydraulic cylinder scratch model is developed based on an analysis of the characteristics of scratch specimens, with width, depth, and length as the key parameters for characterization. The novelty of this work lies in its dedicated scratch-focused approach, which systematically quantifies the impact of scratch geometry on leakage through CFD simulation and experimental validation. Using the QY110 truck crane support cylinder as the case study, a simulation model for internal leakage due to scratches in hydraulic cylinders is established. Orthogonal experiments are conducted to analyze the flow field of the scratch-induced internal leakage using Computational Fluid Dynamics (CFD) techniques. The impact of scratch characteristics on internal leakage is investigated. The results demonstrate that leakage increases monotonically with both depth and width, while leakage initially increases and then decreases with an increase in length. Scratch defects are artificially introduced into the experimental support cylinder, followed by internal leakage experiments. The discrepancy between experimental and simulation results is within 30%, which verifies the effectiveness of the orthogonal simulation analysis.</p>