Ultrasonic image-forming system beam-forming method includes: to reconfigure the different beam forming example in aperture to be increased the number of channel by i and formed the hole absolute atmosphere Wave beam forming example while reducing the focus of sampling rate Yu increased depth II) number increase array element, it is that multiple composite components form single array-element single-channel absolute atmosphere Wave beam forming example that the composite component in two channels of part, which forms the focus that absolute atmosphere Wave beam forming example in hole has increased depth, And/or III) define permissible delay error for the focus of each depth and each beam forming example in base stage channel is selected to form the hole to form hole and selection additional channel in one delay error of Wave beam forming example and be less than permissible delay error relative to bottom.
