This open access book first introduces the explosive characteristics of combustible gas in the process industrial device, and then introduces the influence law of structural effect on gas explosion characteristics and deflagration to detonation process, and finally introduces the suppression mechanism and protection technology of gas explosion. This book takes the process industrial gas explosion characteristics and its protection as the research object, and discusses the gas explosion characteristics and its protection theory in details. This book can be used as the undergraduate and graduate textbook of safety engineering and related engineering majors in universities, and also as a reference for scientific research staff in safety science and engineering and related disciplines, and also for the reference of safety technology and management personnels.