Abstract:The Acer truncatum Bunge leaves are rich in fatty acids and nutritional composition.The experiment tracked the tannins in the Acer truncatum Bunge leaves during the growing period （one month）.The single factor experiments and orthogonal optimization experiments were carried out by the colorimetric method of pretreatment of different levels of heating time，temperature，and ratio of feed to liquid by the method of sodium tungsten-phosphomolidate.Through the law of the change of the determination of tannin content，the optimized test conditions were obtained：bath temperature 70 ℃，the heating time 40 min and the sample dilution multiple 1∶90（g/mL）.The content of tannin extracted from the Acer truncatum Bunge leaves was 338.9 g/kg.