The invention discloses a construction method of backward construction after every single step for a light-section tunnel, and belongs to the field of tunnel construction. The construction method includes the following steps that a tunnel face of the light-section tunnel is tunneled forward, meanwhile, initial supporting is constructed to the tunnel, and second lining concrete cast is conducted ona constructed tunnel bottom section of the rear; after the tunnel face is tunneled and supported to a certain length, excavation of the tunnel face is suspended, a delivery pump pipeline is laid to the tunnel face from the side wall of the tunnel, the tunnel bottom is excavated back from the tunnel face, and after waste materials at the tunnel bottom are cleared, concrete at the tunnel bottom iscast backwards until the position of a constructed tunnel bottom structure reached through the delivery pump pipeline; tunneling of the tunnel face of the front and secondary lining construction of the rear are continued; and the steps are repeated until whole tunnel construction is completed. According to the construction method of backward construction after every single step for the light-section tunnel, interference between tunnel face tunneling and tunnel bottom construction in the limited operation space of the light-section tunnel is avoided, thus tunnel bottom and tunnel face operationis non-cross, the operation efficiency and construction progress are effectively improved, and the construction cost is lowered.