Disclosed is a prestressed concrete on-site pouring hollow slab filled with light material combined unit, which comprises light material combined unit, upper layer reinforcing steel bar, lower layer reinforcing steel bar, tendon, blind beam reinforcing steel bar and concrete. The light material combined unit consists of light tubes and connection bar, which is arranged between the upper layer reinforcing steel bar and the lower layer reinforcing steel bar, the combined unit tubes is in the same direction with the bigger bending moment within the slab, The blind beam is arranged at intervals of a certain distances, in which the tendon is centralized laid. Said on-site pouring slab has the advantages of both the prestressed structure and the hollow slab structure, has high hollow percentage, implements one time concrete pouring moulding, is suitable not only for one-way slab, but also for two-way slab. The slab has big span, light weight, good heat and sound insulation effects, good reliability, shock resistance and crack resistance.