Based on the basic principle of Park equation, the basic equation of the 6-phase synchronous generator is established, and d-axis and q-axis equivalent circuits of 6-phase synchronous generator are obtained. Comprehensive mutual reactance in equivalent circuits reflects the magnetic coupling function between double Y of the 6-phase synchronous generator. It consists of armature reaction reactance and comprehensive mutual leakage reactance. Through the analysis of single Y operation (the other Y no-load ) and double Y operation of the 6-phase synchronous generator, it can be obtained that double Y synchronous reactance is equal to the difference of 2 times single Y synchronous reactance and self leakage reactance. Taking the example of no-load short-circuit test, the characteristic curve of 6-phase synchronous generator, the d-axis synchronous reactance, the self leakage reactance, and the short-circuit ratio are measured. The steady-state electromagnetic parameters of the 6-phase synchronous generator are verified with the electromagnetic theory analysis and practical operation characteristics.