A novel scale indicator calculation method is introduced based on fractal theory in order to solve the problems of too much subjectivity and great calculation difficulty in indicator extraction by using conventional electromagnetic environment measurement method. After demonstrating the fractal characteristics of the electromagnetic environment, the fractal dimension calculation method based on mathematical morphology is investigated, and then applied to calculating the electromagnetic environment complexity index. The calculation results indicate that this method can provide multidimensional information to distinguish the electromagnetic environment complexity in both space and time.