The invention discloses a subsidiary inverted excavation construction method for an urban subway station under the complex environment and relates to the field of tunnel excavation. The method comprises the following steps of before inverted excavation construction, layering and segmenting the section according to the size of the section; before excavation, reinforcing a front soil body of a first-layer pilot tunnel excavation face by adopting deep-hole pre-grouting; performing excavation and primary support on a first-layer pilot tunnel by adopting an upper-lower step method; after the excavation and primary support of the first-layer pilot tunnel 6 are completely finished, performing excavation and primary support of a second-layer pilot tunnel, repeating the operation for a third-layer pilot tunnel, and performing next-layer pilot tunnel construction according to the mode; after the excavation of pilot tunnels of all layers are finished and the deformation of the primary support 2 is stabilized, dismantling a temporary support by adopting a piecewise interval method. According to the subsidiary inverted excavation construction method disclosed by the invention, the risk of the inverted excavation construction is greatly reduced, the construction safety is guaranteed, and the concealed excavation construction method of the tunnel is enriched; meanwhile, the parallel operation of demolition of an open excavation section and a concealed excavation section is also realized, so that the construction period is shortened.