The utility model provides a rain -proof cover of dust sensor, belongs to the gas sensor field, the shell is installed at bottom of the car body, the shell front end is equipped with the air inlet, the shell front end is equipped with the gas outlet with the air inlet with one side department, promptly air inlet and gas outlet symmetric distribution, all install on air inlet and the gas outlet and prevent the wadding net, prevent wadding net periphery on air inlet and the gas outlet and still install the wind cap, the air inlet is connected with the inlet box, inlet fan is installed to the inlet box upper end, the inlet box is connected with the one end of pipe, the other end of pipe with detect the groove and be connected, it is connected with the gas outlet to detect the groove, it has a through -hole to detect groove one side, laser emitter installs and is detecting groove one side, and laser can pass the through -hole that detects on the groove, laser detection device is installed to the through -hole other end. In the device passes through the air suction sensor of inlet fan in with the atmosphere, and then detect the dust concentration in the air through laser.