The invention provides an ultrasound synthesis method and application and a shear wave ultrasound elastography method and application and belongs to the technical field of ultrasound. The ultrasound synthesis method includes the following steps that an ultrasound transducer array emits at least two ultrasound beams stretching in different directions; grating lobe angels of the ultrasound beams are adjusted respectively according to the emitted ultrasound, and grating lobes of the ultrasound beams are overlapped with main lobes of adjacent another ultrasound beams. According to the method, no grating lobe needs to be restrained, the grating lobes and the main lobes of other ultrasound beams are combined into new ultrasound beams with higher energy, and therefore the utilization rate of energy can be greatly increased while imaging quality is improved.