The invention discloses a device to carry out weeding, pest eliminating and sterilizing by using microwaves. The device consists two relatively parts of a microwave radiator and a power. The microwave radiator part comprises a bugle antenna, a resonance cavity, a permatron, a circulating device, a coupler, a control panel, a running device and an anti-leakage device, etc. The power part comprises a transformer and a rectifier, etc. When working, the microwave radiator moves and the power part does not move together with the microwave radiator; the power part feeds energy to the microwave radiator through a flexible feed wire, thus reducing the weight and size of the microwave radiator, being convenient for operating in a narrow and small space (such as a greenhouse, etc), being more convenient for miniaturization and mechanization and being beneficial to improve the planting manufacture efficiency of a protection field. The device adopts microwaves to prevent disease and pest with the advantages of convenient operation, no residue, friendly environment, which is helpful for carrying out nuisanceless agricultural production, suitable for the nuisanceless production like gardening plants such as vegetables, fruits and flowers, etc., and plants like medicinal materials, etc., in particular to the fine agricultures of the protection filed, etc.