Abstract: The agricultural diesel engine worked for long time in bad environment of high torque，high mechanical load and thermal load，high dust，and more than 85% of the engine had fault，such as early wear，fuel consumption high，unable to work，and the vast majority of above cases were related to air intake system design.Based on the actual production，through the author′s experiences for many years engaging in engine air intake system supporting and designing，the agricultural diesel engine intake system supporting，design principles and methods，and matched typical examples of application were described，in order to providing reference for the agricultural machinery design professionals and user.