The electromagnetic compatibility（EMC）and the control strategies of EMC are introduced. The principle，occasion and method of the prediction analysis for EMC are introduced，then the technologies of EMC，including grounding，lap joining，arrangement，wiring，shielding，filter，lightning protection are analyzed. The effective engineering design is proposed from the professional point of view，and is described based on the applications. The basic principles of equipment and cable arrangements are introduced. The advices on how to improve the EMC level for designers are proposed.