As one of the crucial human aspects, individual decision-making behavior that may affect the quality of a software project is adaptive to the environment in which the individual is. However, no comprehensive reference framework of the environmental factors influencing individual decision-making behavior in software projects is presently available. This paper undertakes a systematic literature review (SLR) to gain insight into existing studies on this topic. After a careful SLR process, 40 studies were targeted to solve this question. Based on these extracted studies, we first provided a taxonomy of environmental factors comprising eight categories. Then a total of 237 factors are identified and classified using these eight categories, and some major environmental factors of each category are listed in the paper. The environmental factors listing and the taxonomy can help researchers and practitioners to better understand and predict the behavior of individuals during decision making and to design more effective solutions to improve people management in software projects.