Abstract: An ultrasonic-microwave alternant method for extracting dihydroquercetin from larch wood was applied by using dihydroquercetin yield as an index. The extraction was conducted using 60% ethanol as solvent，the solid to liquid ratio of 1∶12，and soakage time of 3 hours. The microwave treatment time was 10 min，ultrasonic treatment time was 40 min respectively and the extraction was performed one time with the strongest power. The ultrasonic-microwave alternant extraction was performed by ultrasonic extraction for 40 min and then microwave extraction for 10min. The yield of dihydroquercetin with ultrasonic and microwave extraction were 0.034% and 0.074% respectively，while that of ultrasonic-microwave alternant extraction was 0.12% which is much higher than ultrasonic and microwave extraction alone. By scanning electron microscopy (SEM) observation，the ultrasonic-microwave alternant effect of substance dissolution from plant cell was the most obvious among the above-mentioned three methods.