The invention provides an automatic chemical fertilizer bag opening and discharging machine, and relates to the technical field of bag opening and discharging devices. The machine comprises a rack, a cutting assembly, a screening assembly and a discharging conveying assembly, the cutting assembly is arranged at the top of the rack, the discharging conveying assembly is arranged at the bottom of the rack, the screening assembly is arranged on the portion, between the cutting assembly and the discharging conveying assembly, of the rack; the screening assembly comprises a vibrating box, vibrating screens, guide rails, a main shaft and throwing blocks, the vibrating box is elastically connected to the rack, the plurality of vibrating screens are arranged in the vibrating box, the plurality of guide rails are arranged on the vibrating screens, the main shaft is rotationally connected to the side wall of the vibrating box, the throwing blocks are arranged at the two ends of the main shaft, and the main shaft is connected to a first motor. Through the arrangement, a bag and a material can be separated more thoroughly, the number of cakes in the chemical fertilizer treated by the automatic chemical fertilizer bag opening and discharging machine can be reduced, the operation is simple, and the working efficiency is relatively high.