This study attempts to characterize the electromagnetic compromising emanations from Laser Facsimile. Electromagnetic radiation is inevitable when electronic equipment works. The radiations can deteriorate the performance of a part of device itself or of another system. This phenomenon is a subject in the field of electromagnetic compatibility (EMC). But concerning people who process classified information, there is another threat that such electromagnetic radiation could be intercepted, deciphered and finally reveal the data being processed by the equipment. In this paper, electromagnetic side channel of laser facsimile and countermeasures are analyzed and discussed. It shows that the electromagnetic side channel of electronic information equipments is a real threat of information security.