The invention discloses a reinforcing method for a concrete structure based on gradient releasing prestress. The reinforcing method comprises the following steps: S1, embedding a tensioned prestress fiber reinforced composite material (FRP) batten into a prefabricated slot of a reinforced concrete structure, wherein the prestress FRP batten and a concrete beam are bonded by means of a bonder within an appointed range; S2, releasing part of or all prestress after the bonder is cured and then filling two sides of a section of a prestress releasing end part of the FRP batten with the bonder of acertain length for curing according to a design structure of an actual need; and S3, releasing residual prestress after the newly filled bonder is cured, and filling the newly bonding end part with the bonder to form a bonding section as an anchorage device. The reinforcing method has the advantages of being simple in structure, convenient to construct, good in effect and the like.