The invention discloses an electrical oversized target scattering estimation method of mold calibration based on high-frequency and low-frequency algorithms. The electrical oversized target scattering estimation method includes 1, estimating electromagnetic scattering characteristics of a low frequency band of a given target based on the high-frequency algorithm; 2, estimating electromagnetic scattering characteristics of a low frequency band of a given target based on the low-frequency algorithm; 3, comparing estimation results of step 1 and step 2, and determining whether a peak value difference and an average difference of the estimation results are in a setting range or not; 4, if not, performing mold calibration of an established mold through the high-frequency algorithm according to the estimation result of the low-frequency algorithm; and 5, if so, estimating the electromagnetic scattering characteristics of a needed high frequency band by using the high-frequency algorithm so as to acquire a result of the target scattering characteristics. By the aid of the electrical oversized target scattering estimation method, accuracy and speed can be balanced, and the electromagnetic scattering characteristics of the electrical oversized target can be estimated accurately and rapidly.