The invention relates to a method for preparing AgSbTe2 thermoelectric compound powder, in particular to a sonochemistry method for preparing the AgSbTe2 thermoelectric compound powder. The method is characterized by including the following steps: 1) deionized water is used as solvent, and analytically pure AgNO3, C4H4KO7Sb-1 / 2H2O and TeO2 are added to and stirred and mixed with the solvent, thereby obtaining mixed liquid A; 2) ammonia is poured into the mixed liquid A, and the mixture obtained is processed by ultrasound for 30 minutes, thereby obtaining mixed liquid B; 3) reducing agent NaBH4 is added to and thoroughly reacts with the mixed liquid B under ultrasound for 2 to 6 hours, thereby obtaining a product C; 4) the product C obtained in the step 3) is centrifuged and is dried in a vacuum drying oven to obtain a precursor of the AgSbTe2 thermoelectric compound; and 5) the precursor obtained in the step 4) is processed by reduction in hydrogen at 450 to 500 DEG C for 1 to 4 hours, thereby obtaining the AgSbTe2 thermoelectric compound powder. The method has the advantages of low-cost and easily accessed raw materials, simple and easily controlled technology, short reaction time, low energy consumption, high safety, favorable repeatability and no pollution, and can be used for large-scale preparation.