The existence of floating ice in ice storage tanks in an ice storage system affects the normal operation of the ice storage automatic control system. For the ice storage tank in an ice storage system, the ice “problem”, puts forward the way of melting ice in an ultrasonic assisted manner. This paper establishes a polynomial mathematical model of observation data changes over time, by setting a variable’s value used to model the polynomial fitting method. It could be used in the design and operation index model or higher polynomial model fitting process of melting ice. Ultrasonic wave is used to solve the floating ice problem of ice storage tank in the operation of ice storage, and the effects of ultrasonic power density, ice-water ratio, ice size, initial ice amount and other parameters on the characteristics of ice melting are tested and analysed through experiments, which provides an important reference for the practical application of this technology. It is found that the ultrasonic wave can obviously promote and strengthen the melting of ice, and the influence of power, ice–water ratio and ice size conforms to the normal theory and practice law. The greater the power, the smaller the ice–water ratio and the smaller the ice size, the faster the melting speed will be. Due to the multiple effects of technology and economy, the power density has an optimal value, which needs to be optimised according to the actual situation in the application. For large size ice, the promotion effect of high-power ultrasonic on melting ice is more obvious.