The present invention relates to a beamforming method used in an ultrasonic imaging system, the method comprises: receiving the reflected echo signal from the reception my by the transducer elements of the probe; transmit the received reflected echo signal by the transducer element to a receiving and processing channel to be amplified and AD converted to obtain digital echo data; storing the digital echo data into the memory; generating apodization parameters by the apodization parameter real time calculation device based on the digital echo data; and performing beamforming by the receiving and beamforming module by involving the generated apodization parameters. Memory resources of the system can be saved by the technical solution of the present invention, and the speed of parameter loading can be increased when the probe is switched by the system.