The invention relates to a floating upper-filtering style filter with backwashing pollution-cleaning capability and a using method thereof, relating to sewage disposal technique field. A tank body is respectively welded with a manhole, a water outlet, a backwashing water inlet, a draining outlet and a water distributor, and the tank body is tightly fixed with a water filter and is connected with a vent flange and is embedded with a vision lens. The water outlet is connected with a water draining pipe through a water draining valve; the backwashing water inlet is connected with a water inlet pipe through a backwashing water inlet valve; the water inlet pipe is connected with the water distributor through a water inlet valve; a backwashing gas inlet is connected with a gas inlet pipe through a gas inlet valve; the draining outlet is connected with the filter body through a connecting valve, and the filter body is connected with a seal cylinder and the seal cylinder is connected with a draining pipe all through draining valve flanges; and the filter body is fixedly connected with a strainer film. The filtering material adopted in the method comprises polystyrene, pentane vesicant and cinnamene free monomer with a proportion less than 1. When in sewage disposal, the filtering materials are filled and draining is closed, and connection is done and gas is supplied, and then the water inlet valve is backwashed and the water draining valve and the inlet valve are opened; when pollutions cleaning, the water draining valve and the inlet valve are closed, and draining is opened and connection is done and the water inlet valve and the gas inlet valve are backwashed. The invention can be applied to sewage disposal, and the upper filtering design occupies less space and the filtering materials have a long service life for pollution cleaning.