According to the demand of comprehensive protection of ship’s electromagnetic field, this paper studies the cou- pling characteristics of magnetic field protection and electric field protection. Eleven sources of electromagnetic field are summed up, and the coupling relations produced by various electromagnetic field sources are analyzed. Based on the mathematical analysis models of coupling of magnetic field and electric field, the coupling characteristics of magnetic field and electric field are simulated and analyzed. This paper points out that comprehensive protection of ship’s magnetic field and electric field should be implemented by combining all kinds of control measures.