According to the analysis on the variety of complex electromagnetic environment elements and the differences of their effects on the equipments, from the aspects of time, frequency，power，modulation and polarization parameters of electromagnetic signals, a new evaluation method on electronic jamming signal environment based on Signal to Jamming Ratio(SJR) is proposed. A new evaluation index based on modulation matching coefficient, polarization matching coefficient and relative power intensity is established, which achieves the consistency among electromagnetic environment characteristic, equipment technical features and evaluation results. Simulation tests are performed to validate the feasibility and rationality of this method.