Environmental-friendly organic solar cells based on alcohol-soluble conjugated materials have recently received great research attention. In this work, newly synthesized alcohol-soluble C70-based fullerene derivative (PC71BO15) for eco-PSCs processed is presented. The PCEs of PPDT2FBT-A:PC71BO15-based eco-PSCs up to 2.51%, which is the top value reported to date for aqueously processed PSCs, was achieved due to the desirable stacking behavior and enhanced photon absorption ability. At the optimized water/ethanol composition (v/v = 15:85), the PCE of the PC71BO15-based eco-PSCs is 72% higher than that of the PC61BO15-based counterparts, due to improved light absorption. More importantly, the PC71BO15-based eco-PSCs show much better tolerance in their PCEs to the water/ethanol ratio. For example, PC71BO15-based eco-PSCs at a 30:70 water/ethanol ratio maintain 89% of the optimum performance at a 15:85 ratio, whereas only 45% for PC61BO15-based devices. Different aggregation behaviors between PC71BO15 and PC61BO15 in blend film induced large difference in terms of water-tolerant behavior, which is carefully explored by electrical, optical and morphological characterizations. The PC71BO15-based eco-PSCs with eco/human-friendly water/alcohol processing in ambient conditions can have excellent photovoltaic performances reproducibility due to the high water composition-tolerance.