The invention provides an ultrasonic welding method. The ultrasonic welding method comprises the steps that whether the ultrasonic heights of all pairs of pre-welded components are the same or not is checked; the components with the same ultrasonic height are screened out, and ultrasonic equipment with the corresponding frequency is selected according to the ultrasonic height of each pair of components; as for the components different in ultrasonic height, whether parts of welded faces which meet the fixing requirement and have the same ultrasonic height exist or not is checked, and if yes, ultrasonic equipment with the corresponding frequency is selected according to the ultrasonic height of the parts of welded faces; if not, whether the radian of the welded faces is smaller than a first set value or not is checked, and if yes, ultrasonic equipment with the corresponding frequency is selected according to the maximum ultrasonic height of the welded faces; and ultrasonic welding is conducted according to the assembling sequence on the basis of the ultrasonic equipment which has the corresponding frequency and corresponds to each pair of components. The ultrasonic welding method is suitable for ultrasonic welding of multiple workpieces and different welded faces.