An ultrasonic imaging apparatus, a method for detecting a shear index of a vascular wall using ultrasonic waves, and a computer readable storage medium are provided. The method comprises: transmitting ultrasonic waves to an region of interest comprising a vessel; receiving the ultrasonic waves to obtain echo signals; acquiring an ultrasonic image according to the echo signals; acquiring particle jet velocities of a plurality of points in the vessel, the particle jet velocity comprising flow velocity and flow direction; determining a vascular wall in the ultrasonic image; acquiring a position to be detected of the vascular wall; calculating, according to particle jet velocities of a plurality of points near the position to be detected, the shear index of the position to be detected of the vascular wall; and displaying the ultrasonic image and the shear index of the vascular wall.