The invention discloses an automatic adjusting shielding spraying machine for relay intercropping of different crops applied to a field and an operation method, and relates to the field of agricultural plant protection. The automatic adjusting shielding spraying machine comprises a controller, a sampling module, an execution module, an interaction module, a function module, a rack and a pesticidebox; and the automatic adjusting shielding spraying machine is suitable for plant protection operation during relay intercropping of the different crops, and is suitable for plant protection sprayingoperation from herbicide spraying after seed sowing to crop harvesting. During working of the automatic adjusting shielding spraying machine, the height of a spraying frame, the length of a spraying rod and the length of a fog blocking curtain can be automatically adjusted according to the corresponding crops. The situation that crop growth is affected due to pesticide pollution during intercropping of monocotyledons and dicotyledons can be effectively prevented, the pesticide utilization rate is increased, and resources are saved.