A cavity formwork member for concrete filling, comprising an upper plate (1), surrounding side walls (2), and the upper plate (1), surrounding side walls (2) form an open cavity formwork, characterized in that The cavity formwork has at least two prefabricated panels (3), and there are at least two conjoined prefabricated panels in the prefabricated panels (3), and the prefabricated panels (3) are combined into an open cavity or a closed cavity , the prefabricated slabs (3) are connected by connectors (4) as a whole, the formwork is composed of the prefabricated upper plate (1) and the prefabricated surrounding side walls (2), and each prefabricated slab (3) stretches There is at least one connecting piece (4), adjacent prefabricated panels (3) are connected to each other by the connecting piece (4), and the surrounding side walls (2) are composed of more than two prefabricated panels (3). It is suitable for the use of cast-in-place reinforced concrete or prestressed reinforced concrete hollow floors, roofs, walls, foundation floors and hollow bridges, especially for hollow beamless floors.