An automatic anti-flooding barrier , comprising: - a support frame, comprising a primary beam , extended along a first longitudinal direction, and a pair of secondary beams , protruding from the primary beam along a second transverse direction, perpendicular to the first longitudinal direction, and mutually spaced along said first longitudinal direction; and - a platform , hinged to the primary beam and movable from an inactive position, wherein said platform lies on a plane parallel to the plane defined by the longitudinal and transverse directions, to an active position, wherein said platform lies on a plane perpendicular to the plane defined by the longitudinal and transverse directions, said platform being suitable, when in the active position, to prevent the passage of a fluid therethrough; the automatic anti-flooding barrier comprising a pair of linear actuators , each having a first end hinged to a respective secondary beam , and the opposite end hinged to the platform , said actuators being adapted to thrust the platform towards said active position when the platform is in a position other than the inactive position, characterized in that the linear actuators are configured in such a way that, in the inactive position of the platform , they lie substantially parallel to the platform ; and in that the automatic anti-flooding barrier further comprises a float , integral with a face of the platform facing the secondary beams , said float being configured to impart a thrust to the platform in the direction of the active position thereof, when said float is at least partially immersed in a fluid. - a support frame, comprising a primary beam , extended along a first longitudinal direction, and a pair of secondary beams , protruding from the primary beam along a second transverse direction, perpendicular to the first longitudinal direction, and mutually spaced along said first longitudinal direction; and - a platform , hinged to the primary beam and movable from an inactive position, wherein said platform lies on a plane parallel to the plane defined by the longitudinal and transverse directions, to an active position, wherein said platform lies on a plane perpendicular to the plane defined by the longitudinal and transverse directions, said platform being suitable, when in the active position, to prevent the passage of a fluid therethrough; the automatic anti-flooding barrier comprising a pair of linear actuators , each having a first end hinged to a respective secondary beam , and the opposite end hinged to the platform , said actuators being adapted to thrust the platform towards said active position when the platform is in a position other than the inactive position, characterized in that the linear actuators are configured in such a way that, in the inactive position of the platform , they lie substantially parallel to the platform ; and in that the automatic anti-flooding barrier further comprises a float , integral with a face of the platform facing the secondary beams , said float being configured to impart a thrust to the platform in the direction of the active position thereof, when said float is at least partially immersed in a fluid. <EOS>