The invention discloses a constructing device for bottom concrete of a tunnel pressure steel pipe. The constructing device comprises a pressure steel pipe and is characterized by also comprising a pressure steel pipe stiffening ring, longitudinal structural reinforcing bars, an annular structural reinforcing bar, self-compacting concrete and vibrating guide cages; the pressure steel pipe stiffening ring is arranged outside the pressure steel pipe; the annular structural reinforcing bar is arranged at an outer ring of the pressure steel pipe stiffening ring; the longitudinal structural reinforcing bars are axially arranged in the self-compacting concrete; the annular structural reinforcing bar and the longitudinal structural reinforcing bars are bound and fixed; the vibrating guide cages are arranged in the self-compacting concrete, are welded and fixed with the longitudinal structural reinforcing bars and are close to the pressure steel pipe stiffening ring; and each vibrating guide cage is formed by connecting longitudinal round steels with an annular round steel. The constructing device for the bottom concrete of the tunnel pressure steel pipe, disclosed by the invention, is applied to construction of the bottom concrete of a large-sized pressure impact resisting tunnel pressure steel pipe; and the pouring efficiency of the concrete and the fullness of the bottom of the pressure steel pipe are improved to a great degree.