The invention relates to the field of tunnel engineering, in particular to a design analysis method for an auxiliary support system of a tunnel steel frame. A mechanical analysis model of the auxiliary support system of the steel frame is built according to an action mechanism of the auxiliary support system of the steel frame; and foundation loads of arch feet, settling amounts of the arch feet, internal forces of the sections of a connecting longitudinal beam, and stress and deformation situations of foot-locking members and underlying foundations of the foot-locking members on the steel frame in different working conditions under the support action of the auxiliary support system of the steel frame can be obtained through a force method. A tunnel designer can perform checking calculation on bearing forces of foundations of the arch feet, the settling amounts of the arch feet, the strength of the connecting longitudinal beam and the foot-locking members, and bearing forces of the underlying foundations of the foot-locking members on the steel frame in different working conditions by utilizing the obtained foundation loads of the arch feet, settling amounts of the arch feet, internal forces of the sections of the connecting longitudinal beam, and stress and deformation situations of the foot-locking members and the underlying foundations of the foot-locking members on the steel frame, and finally the design of the auxiliary support system of the steel frame is finished.