The present invention discloses a constructional formwork system including an internal climbing unit disposed inside a building body. The internal climbing unit includes a second climbing system and ajacking system; the second climbing system and the jacking system are both provided with a construction operating platform, a construction device and a construction material receiving platform; the internal climbing unit also includes a hoisting system and a lifting device; the hoisting system is provided with a construction operating platform, a construction device and a construction material receiving platform; the lifting device is used for providing an upward traction force for the hoisting system to enable the hoisting system to be lifted in the vertical direction along a core tube or hoistway in a building; and the constructional formwork system also comprises connecting members for fixed connection between the hoisting system and the building. The formwork system is easy to implement, and has better economic properties while ensuring the construction efficiency compared with the conventional formwork system.