Abstract: This article takes the Siemens PLC control system applied in a zinc electrowinning intelligent crane in the non-ferrous metallurgical industry as the research object.Based on the strong magnetic environment in which the control system is actually applied on site, the communication faults caused by complex interference factors on site are analyzed and studied.It provides on-site solutions for relevant engineers and technicians to prevent external interference of PLC control system and improve EMC performance of the system, which has certain practical significance.