The invention relates to the technical field of tunnel excavation construction and provides a construction structure based on the shielding lateral split starting in an underground excavation area. The construction structure is applied to a construction method based on shielding lateral split starting in the underground excavation area and further comprises a tunnel for soil transportation and parking of an accumulator car, a shield assembling and soil discharging shaft, a shield translation cross channel, a split starting trolley arrangement bored tunnel, a shield veering bored tunnel, a shield starting position bored tunnel and a shield tunnel. The construction method based on shielding lateral split starting in the underground excavation area, provided by the invention, is characterized by safe excavation, high construction speed, no influence on environment and flexible starting position; a starting well needs not be arranged in a built station structure or independently arranged; the shield can start on any position; the shield starting line and the designed central line direction of the tunnel need not be kept constant; the starting position needs not be arranged in a boundary line of road and is kept away from the position under the urban main road.