Abstract: The aim was to prioritize the ultrasonic-assisted extraction technology of phloridzin in Lithocarpus polysachyus Rehd.. By controlling the change of mono factors, the optimal range of the solid-liquid ratio, ethanol concentration, extraction temperature and extraction time were validated with ultrasonic-assisted extraction in Lithocarpus polysachyus Rehd.. And then L₉(3⁴) orthogonal design and verification experiments were used to determine the optimal extraction process. Factors influencing the extraction yield of phloridzin in Lithocarpus polystachyus were as follows: extraction time > ethanol concentration> extraction temperature > solid-liquid ratio. The optimal extraction conditions were as follows, extraction temperature 45℃, solid-liquid ratio 1:30, extraction solvent 70% ethanol, and extraction time 35 min. Under these extraction process conditions, the extraction yield of phloridzin was 1.421% and the content of phloridzin was 3.797%. The RSD of verified experiment was 0.881%, which indicated that the optimal extraction process had good reproducibility and stability.