Bridge steel with bainite structure and preparation method thereof

The invention discloses bridge steel with a bainite structure and a preparation method thereof, and relates to the technical field of steel production, a steel plate comprises the following chemical components in percentage by mass: 0.15-0.17% of C, 0.20-0.40% of S i, 1.0-1.3% of Mn, less than or equal to 0.020% of P, less than or equal to 0.010% of S, less than or equal to 0.050% of A < t >, less than or equal to 0.0080% of N, 0.010-0.020% of Nb and the balance of Fe and inevitable elements, and converter smelting is carried out; performing LF refining; continuously casting a plate blank; carrying out stack cooling on the plate blank; heating the plate blank; controlled rolling; and controlling cooling. According to the bridge steel with the bainite structure and the preparation method of the bridge steel, the bainite bridge steel is manufactured by adopting controlled rolling and controlled cooling, so that the problem that a bridge steel product temporarily does not relate to a regulation and control proce