Recent decade, small molecule organic solar cells have attracted lots of interests. Especially, the synthesis of novel p-conjugated small donor-acceptor molecules and optimization of small molecule organic solar cells processing conditions have been investigated in detail. Although some important progress have been reached, it was still a challenge for further improving their power conversion efficiency, durability and cost effectiveness. This review provided the scientific community with both general and in depth information on the relationships between structure and property depended on processing conditions, for example, donor/acceptor (D/A) weight ratios, solvent and treatment. These drew some rules for process of small molecule organic solar cells, which were very important for further improving the performance of small-molecule organic solar cells. (C) 2017 Elsevier Ltd. All rights reserved.