The invention discloses a double-T-shaped reinforced concrete prefabricated bottom plate and a composite slab manufactured by the same. The double-T-shaped reinforced concrete prefabricated bottom plate comprises prefabricated bottom plate concrete, prefabricated bottom plate bottom ribs, prefabricated bottom plate bottom rib longitudinal prestressed steel bars, longitudinal stress steel bars in the prefabricated bottom plate, and transverse structural steel bars in the prefabricated bottom plate. Hole forming and steel bar penetrating are not needed, the prefabricated bottom plate longitudinal structural steel bars are tightly connected at spliced seams, thus the prefabricated bottom plate is reasonable in overall stress, large in initial rigidity and high in bearing capacity, meanwhile tedious manufacturing processes of hole formwork erecting and removing when holes are reserved in an existing ribbed reinforced concrete prefabricated bottom plate and steel-ribbed concrete prefabricated bottom plate rib are omitted, the process of steel bar penetrating on a construction site is omitted, the process of arranging spliced seam anti-cracking steel bars and other processes for treatingthe spliced seam structural steel bars are further omitted, formwork erecting is easy and convenient, manufacturing and construction working procedures are simple, the construction difficulty is low,the construction time is saved, and the construction efficiency is high.