This paper describes how asymmetric trust develops and changes in time in cooperative relationships between large enterprises and SMEs in China. A model is developed on the basis of in-depth case studies of cooperation between six SMEs and five large firms in China. The data sources reveal how Chinese SMEs use trusting behavior to overcome trust asymmetry in negotiations in order to exploit business opportunities. This study provides insights into the micro-processes of building trust at three consecutive stages of the cooperation process. For each stage, the paper describes the perception of trust asymmetry of cooperating large firms and SMEs, the trust building behavior of SMEs, and the response to that behavior from large firms. The paper analyzes how large firms and SMEs deal with asymmetric trust to develop longlasting cooperative relationships.