A reverse well-flushing valve aims to overcome the defects in conventional reverse well-flushing valves that a valve ball is inclined to skew in slant wells or horizontal wells, sundries are easier to deposit on a sealing surface formed by a valve ball and the conical surface of a valve seat, and the sealing reliability of the conventional reverse well-flushing valves is poor. The reverse well-flushing valve is characterized in that a baffle (2) and spacer sleeves (5) are mounted in sequence between the lower parts of steps of the inner holes of an upper connector (1) and the upper end of a valve seat (7), an axial liquid flowing hole (9) is formed on the baffle (2), a right pole (4) is mounted above a valve ball (6), the upper end of the right pole (4) is mounted inside a center hole of the baffle (2), a spring (3) is mounted on a pole body of the right pole (4), and the upper end of the spring (3) is located on the lower end surface of the baffle (2); and a rubber layer (8) is arranged on the conical surface of the valve seat (7). The utility model has the benefits of reasonable structure and reliable sealing property, meets the requirement for reverse operation of slant wells or horizontal wells, and guarantees regular production of an oil well after construction operation.