This study aimed to explore the effect of ball milling time on the quality of matcha by comparing sensory evaluations, wall breaking rate and color differences of tea powder from different grades of ground tea. The results showed that with the increase of ball milling time, the particle size of tea powder decreased continuously, while the wall -breaking rate increased. However, the chlorophyll content of tea powder decreased gradually, its color changed from dark green to bright green, and particles became softer and finer. The texture of tea soup changed from coarse to smooth, its bitter taste gradually increased, and both bitterness and its persistence increased. When the grinding time was 60 minutes, the tea powders from first-grade and second-grade ground tea achieved wall-breaking rates of 99.11% and 98.86%, respectively, meeting the national standard for particle size in first-grade and second-grade matcha. At a grinding time of 80 minutes, the particle sizes of the two matcha samples (D60) were 13.39 μm and 13.47 μm, respectively, and the wall-breaking rate reached 100% . Considering all quality indicators, the optimal matcha quality was achieved at a grinding time of 70 minutes, with a particle size D60 of approximately 15 μm.