The invention relates to a secondary reheating system for a power-station boiler, wherein a flue at the tail of the boiler is divided into three passages by utilizing an enclosure-wall superheater, and a primary low-temperature reheater, a low-temperature superheater and a secondary low-temperature reheater are respectively arranged in the three passages. Thus, the complexity of the system is lowered, and the temperature regulation of the secondary reheater is realized. Present universal temperature-regulating means are both adopted for the air-temperature regulation of the primary reheater and the superheater, i.e. two regulating modes including a smoke-gas baffle plate and water-spraying temperature decrease. The temperature of the secondary reheating system is simultaneously regulated through the smoke-gas baffle plate and a surface-type heat exchanger. Fed water after passing through a high-pressure heater is sent into a coal economizer, a branch is divided on a pipeline of the coal economizer and is sent into the surface-type temperature-decreasing heat exchanger for heat exchange, and the secondary reheating air temperature is regulated by regulating the water quantity of the branch, so that the outlet-steam temperature of the secondary reheater is controlled within the range of a specified value. The water after the heat exchange of the surface-type heat exchanger is directly returned to an outlet pipeline of the coal economizer and enters a spiral water-cooling wall.