The invention relates to a fan blade step array type ultrasonic shot peening device and method. The ultrasonic shot peening device comprises a step-shaped ultrasonic vibratory equipment array, a shotblasting cavity and a working table; the ultrasonic vibratory equipment array is composed of multiple ultrasonic vibratory equipment in an arranged manner, vibrating heads of the multiple ultrasonic vibratory equipment are arranged to be installed on a vibrating head clamping device in a step shape, and the heights of the vibrating heads are sequentially increased from the middle to the two sides;and the shot blasting cavity is installed on the working table, and the vibrating heads of the multiple ultrasonic vibratory equipment can move to penetrate the bottom of the working table and extends into the shot blasting cavity. According to the fan blade step array type ultrasonic shot peening device and method, the vibrating heads of the multiple ultrasonic vibratory equipment are adopted for forming an array for achieving one-time ultrasonic shot peening on larger surfaces; the box-shaped shot blasting cavity is designed, the bottom of the shot blasting cavity is designed to be in a hopper shape, and the problem about recovering of pills in the large-area ultrasonic shot blasting process is effectively solved; and the large fan blade ultrasonic shot peening efficiency can be effectively improved.