The invention discloses a filtering device for agricultural diesel engine gas suction. The device comprises an upper end cap, a cylinder, a filter element, a lower end cap and a supporting base. The upper end cap is provided with an air inlet filtering screen, the lower end cap is installed at the lower end of the cylinder, the lower end cap is internally provided with a connection rod and a first dust discharge channel, the connection rod penetrates through the cylinder and is connected with a fixing nut, the filter element is installed in a cavity of the cylinder, and an S-shaped ventilation pipeline is disposed between a first filtering material and a second filtering material. An inflow air filtering insertion hole is connected with an air inlet, the lower end of the S-shaped ventilation pipeline is provided with dust discharge holes, the dust discharge holes are connected with a second dust discharge channel, and the supporting base is installed at the lower end of the lower end cap. According to the filtering device for agricultural diesel engine gas suction, three-layer filtering is thorough, the structure is simple and reasonable, the filtering device is applicable to various agricultural machines, dry filtering is adopted, the effect is good, manufacturing cost is low, and installation is convenient.