A novel solar-aided coal-fired power generation system (SCPGS) with direct-steam-generation (DSG) solar field and active composite (AC), i.e. active off-focus plus double-axis, sun-tracking strategy is proposed, where the DSG technology is to reduce the cost and the AC sun-tracking strategy is to improve the performance. It is found that the aperture area of DSG solar field could be saved by 12.18% compared to the HTF solar field. The AC sun-tracking strategy is experimentally verified by stabilizing the heat gain (relative deviation < 2%) under DNI fluctuation (relative variation = 35%). The proposed AC-DSG SCPGS is comprehensively evaluated in references of north-south single-axis (1A) DSG, double-axis (2A) DSG and AC heat-transfer-fluid (HTF) SCPGSs. For performance, the annual solar-to-electrical efficiency of AC-DSG SCPGS is 44.33% higher than that of 1A-DSG SCPGS. For environmental impacts, the saved amounts of CO2, NOx and SO2 emissions of AC-DSG SCPGS are 38.11% more than those of IA-DSG SCPGS. For economics, the levelized cost of electricity (LCOE) of AC-DSG SCPGS is 44.56% lower than that of AC-HTF SCPGS. Eventually, the proposed AC-DSG SCPGS comprehensively stands out of all the reference systems. The present work evidentially provides a potential way for the smart and low-cost SCPGS in future. (C) 2019 Elsevier Ltd. All rights reserved.