The utility model relates to an assembled underground structure mixes stake and precast box type component by prefabricated steel and assembles and form, its characterized in that, precast box type component include at least a standard component, and the modularization geometry of standard component for splicing is located all to stagger to be provided with trapezoidal tenon and trapezoidal tongue-and -groove the horizontal of standard film and longitudinal joint, does prefabricated steel mix the stake and includes front portion, rear portion and pile head, all stagger and be provided with trapezoidal tenon and trapezoidal tongue -and -groove in anterior both sides, and prefabricated steel mixes the tenon of stake and precast box type component and mutually supports with the tongue -and-groove size, the anterior position that is close to at the rear portion is provided with the card support, and after assembling into supporting construction, the card holds in the palm for support position in adjacent position's precast box type component, standard component and prefabricated steel mix the stake and all reserve and have the prevention of seepage injected hole, its cross -sectionform be semi -circular, after the completion was assembled to adjacent component, two prevention of seepage injected holes made up and are a circular channel.