The parabolic trough collectors have been proposed to be integrated into the coal-fired power generation system. In this paper, the optimum outlet temperature of collectors was analyzed on the basis of the best operation conditions of the parabolic trough collectors. Then, the integration mode was worked out for a conventional 300MW coal-fired unit and thermo economical performances were analyzed for the integrated system. The results show that, when solar irradiation is 600W/m², the optimum temperature of collectors is 306.55℃. When water from trough collector mixes directly with water from heat regenerator, the best integration mode is that solar water mixes with water from 3# heat regenerator, which renders 23.6% solar-to-electricity conversion and 5.53 g /kWh. coal-saving consumption.