The invention provides a dust removing device for planting greenhouses. The dust removing device comprises a box body, wherein a gas inlet pipe penetrates through one side of the upper portion of thebox body, a gas outlet cylinder penetrates through the other side of the upper portion of the box body, an arc-shaped water separation plate is arranged on the middle portion of the box body, the bottom portion of the water separation plate is provided with a slurry discharging pipe, and both sides of the gas outlet of the gas inlet pipe positioned in the box body are respectively provided with agas jet heads. According to the present invention, air is subjected to filtering and dust removing by using the water body and the multi-layer filtering plate; and the dust removing device can effectively clear the dust and harmful microorganisms in the air inside greenhouses, promote the photosynthesis of crops, and improve the air quality inside greenhouses.