The invention discloses a drag reduction method of a mobile support shield for urban utility tunnel construction. The mobile support shield comprises a plurality of shield units arranged in sequence,each shield unit comprises shield walls arranged on two side walls of a utility tunnel pit and shield plates arranged on facades of the shield walls, two adjacent shield units can move relatively in the tunneling direction of the utility tunnel pit, and the shield plates of the two adjacent shield units are always staggered and overlapped in the moving process of the shield units. The drag reduction method comprises the following step: filling positions between the shield plates and the side walls of the corresponding utility tunnel pit with slurry. The utility tunnel pit can be supported without pouring retaining piles.