Three integration methods of the trough solar-assisted coal-fired unit power generation (SAPG) system were proposed for a 600 MW supercritical generating unit. The first one is the parallel connection of solar fields instead of high-pressure heaters, the second one is the high-pressure series connection of solar fields instead of high-pressure heaters, and the third one is the low-voltage series connection of solar fields instead of high-pressure heaters. Matlab programming was used to establish a simulation model for power generation in a trough solar-assisted coal-fired power plant. The thermal performance of the different integration methods was simulated and calculated under the power increase mode (PB mode). Comparative analyses of the system’s solar power generation, photovoltaic conversion efficiency, and standard coal consumption rate were conducted under the three integration methods. Results showed that the three integration methods of the SAPG system increased with the direct normal solar irradiance E_DNI. The solar energy introduction scale reached a peak of 192.37 MW, the solar power generation capacity was 59.55 MW, the photovoltaic conversion efficiency reached 20.10%, and the standard coal consumption rate was the lowest 264.44 g/(kW·h). The solar power generation capacity, photovoltaic conversion efficiency, and standard coal consumption rate of the low-voltage series connection integration method are better than those of the high-voltage series connection and the parallel connection integration method when the E_DNI ≤ 482 W/m². The thermal performance index of the parallel integration method is better than that of the other two integration methods when E_DNI ≥ 482 W/m², and the thermal performance index of the high-voltage series integration method is the lowest.