The utility model discloses a synchronous suction filtration device for different grain diameters by layers. The synchronous suction filtration device comprises a filtering cup, a suction filtration bottle and a vacuum suction filtration pump, wherein an opening of the suction filtration bottle is connected with a funnel which is internally provided with filtering plates; a flow guide pipe at the lower end of the funnel is inserted into the suction filtration bottle. The synchronous suction filtration device is characterized in that more than one layer of filters which are connected in series are arranged between the filtering cup and the funnel; the filtering plates are arranged at inlets of the filters; a funnel-shaped flow guide pipe is arranged below the filtering plates; the filtering plates are provided with filtration membranes with different pore diameters; the pore diameters of the filtration membranes are gradually reduced from top to bottom. With the adoption of the synchronous suction filtration device for the different grain diameters by layers, solid-liquid separation on the same sample can be carried out synchronously according to the different grain diameters; the loss amount of the sample in traditional layered filtration is reduced; the filtration efficiency and the separation efficiency are improved; the sample is effectively prevented from being polluted in a transferring process; the synchronous suction filtration device has very good practicability.