In order to improve the thermal economy of coal-fired units, the integration and optimization were implemented for the coupling mechanism of the parabolic trough solar collector and the regenerative system in conventional coal-fired units. Then the change of additional fuel specific consumption of equipments in 300 MW coal-fired units is analyzed in this paper before and after system integration, based on fuel specific consumption theory, to obtain the change trend under different solar radiation intensity. The results show that the additional fuel specific consumption of high pressure heaters and deaerators decrease with the increase in the solar radiation intensity, while those of condenser and middle/low pressure cylinders are exactly the opposite, and those of high pressure cylinders are essentially unchanged. The additional fuel specific consumption of steam turbine also increases with an increase in the solar radiation intensity, in which the additional fuel specific consumption of steam turbine increases 0.26 g/（kW·h）, and the saved coal reaches 11.26 g/（kW·h）, when the solar radiation intensity is 900 W/m2 in the integrated system design.