Abstract: The conventional methods can not reflect the real influence of the short-wave antennas because a shortwave broadcast station usually has many electromagnetic sources, and the distribution of electric magnetic field (EMF) in the affected area is complicated. A method using unequal mesh-size measurement based on maximum relative error control is proposed. According to the EMF changes nearby shortwave broadcast station and the feasibility of environment, the mesh-size of measurement is determined by the magnitude of the EMF gradient, adopting a high sampling rate by using small grids and a low sampling rate by using bigger grids. This method decreases the workload and keeps the high measurement precision. Applications prove that this method can get good agreements between measurement and theoretical calculation.