It is widely considered that relational capital serves as an important factor to foster collaboration in supply chain context. However, current knowledge on relational capital mechanisms which affects firm performance remains unclear. According to resource-based view, this article proposes a model to examine how relational capital affect firm performance through enhancing supply chain agility. In addition, the moderating effects of environmental contexts (i.e. munificence, complexity, and dynamism) are taken into consideration when discussing the relationship between relational capital and supply chain agility. Survey data show that supply chain agility fully mediates the association between relational capital and performance. Meanwhile, different kinds of environmental contexts play various moderating roles. Implications and suggestions for future research are provided.