For coordinating of electromagnetic compatibility problems among formation weapon, taking surface ship formation as example to research the electromagnetic compatibility in air defense combat. Through structuring the actual battlefield environment design scenarios, analyzed the influence factors of formation electromagnetic compatibility, based on the typical situation, and analyzed the electromagnetic compatibility problem in formation air defense combat, established formation for electricity and decision model of air defense combat, and carried out actual case analysis. Analysis results show that the model has the availability and feasibility. It establishes evaluation system of the electromagnetic spectrum and has some auxiliary functions for commander decision in air defense command operation plan in the future.