Abstract: Embodiments of the present disclosure provide a method for calibrating a sound velocity applied to a multi-layer variable thickness structure, comprising: constructing a planar multi-layer medium stacked structure and determining a sound velocity of each layer of medium material in the planar multi-layer medium stacked structure; establishing a curved multi-layer medium stacked structure, the curved multi-layer medium stacked structure being arranged with a plurality of discrete elements; at the same time, establishing a fluctuation equation for determining a sound pressure value of each of the plurality of discrete elements; establishing a loss function between the sound pressure value of each discrete element calculated by the fluctuation equation and a measured sound pressure value of each discrete element; performing a gradient descent calculation on the sound pressure value of each discrete element based on the loss function, iteratively updating to obtain a sound velocity value being used as a weighting