The invention provides a sandy gravel stratum shield construction cap-type ground advance reinforcement structure and a sandy gravel stratum shield construction cap-type ground advance reinforcement method. The reinforcement structure is arranged right above a designed shield construction tunnel in a sandy gravel stratum, and a cap-type reinforcement area which covers along the longitudinal direction of the designed tunnel is formed in a ground grouting manner before the shield excavation of the tunnel. The reinforcement method is characterized in that the deep grouting is carried out by adopting a sleeve valve tube grouting way from the ground, and sleeve valve tube grouting holes are distributed as follows: two ground grouting holes are symmetrically formed in two sides along the central line of the designed tunnel in the transverse direction, the distance between the two ground grouting holes is the diameter of the designed tunnel, two columns of grouting holes are distributed at intervals along the longitudinal direction of the designed tunnel, and the distance between every two adjacent grouting holes of each longitudinal column is the radius of the designed tunnel. The cap-type reinforcement area is formed in a grouting reinforcing manner above the tunnel before a shield tunneling machine arrives, the sleeve valve tube is adopted for grouting, the grouting holes are accurately distributed, the effective reinforcement area can be formed after the grouting, and the sandy gravel stratum shield construction cap-type ground advance reinforcement structure and the sandy gravel stratum shield construction cap-type ground advance reinforcement method are proved in the engineering practice to be an economic, stable and high-efficient tunnel shield reinforcement construction structure and an economic, stable and high-efficient tunnel shield reinforcement construction method.