Cooperative behavior is crucial to human’s sustaining development. However, how such behavior occurs and how to maintain this behavior are still less commonly explored. These questions have attracted much focus from different realms such as psychology, biology, economy, and neuroscience. On a day-to-day basis, cooperative behavior can be conceptualized as a decision which is made based on the cognition of others’ (both groups and individuals) psychological state, emotions, and behavioral intention during interpersonal dynamic processes (including both group-level and individual-level). A number of prior researches have proved that, some motivation factors, such as award pursuit, punishment avoidance, desire to gain reputation and exclusion avoidance, benefit the occurrence of cooperative behaviors. In addition, individual differences, such as orientation of social value, sex difference and self-control are crucial prediction source of cooperative behaviors. However, cooperative behaviors in real life often occur in the process of actual interpersonal interaction and interactive information from opponents will certainly influence individual's cooperative behaviors. For example, facial attractiveness and racial characteristic may influence individual's cooperative behaviors through psychological perceptions. Currently, research on factors that influence cooperative behaviors mainly focus on external motivations and individual differences of decision makers, but there are few studies that have examined how actors’ behaviors influence individuals’ cooperative behaviors. Social mindfulness refers to one’s attention towards and protection and satisfaction of others’ autonomous needs in the processes of interpersonal interactions. This construct provides a novel angle for investigating the dynamic processes underlying cooperative behavior. A simulation behavioral experiment was conducted in real contexts of interpersonal interaction, aimed to reveal how and why the behavior agent’s social mindfulness would affect recipient’s cooperative behavior in the perspective of trust. This experiment was a single factor experimental design, 110 participants were randomly assigned to one of two conditions (i.e., 55 participants for high social mindfulness condition; 55 participants for low high social mindfulness condition). SoMi Paradigm was used and individual’s levels of social mindfulness was manipulated by setting the proportion of Player A’s (i.e., confederate) selection of “unique object” and “not unique object”. Trust game was used to measure the level of trust opponent, and public goods game (PGG) was used to test participants’ cooperative behavior. The result showed that regardless of being a receiver or an observer, participants playing with confederate high in social mindfulness were more prone to contribute more resources in PGG. The results of mediation analysis indicated that trust partially mediated the association of social mindfulness with cooperation. Specifically, participants trusted more people with higher levels of social mindfulness, and believed more that they would not betray them, and therefore were more willing to put more resources in public account to maximize collective gains. In conclusion, the current research demonstrate that trust is a crucial mechanism that explain behavior agent’s social mindfulness and recipient’s cooperative behavior. In other words, social mindfulness provides cues of developing trust during interpersonal processes and reduces one’s motivational defense, which leads to the possibility of cooperation and win-win benefit.