Abstract: Trust and cooperation is the base of teamwork in e-commerce and virtual groups. This study used resource dilemmas to examine the development of cooperative behaviors in group tasks. One hundred and eleven students took part in the experiment. The results showed that multi-stage feedback of other members was the most important cue of dynamic decision-making and it was the base of cooperation. The environment uncertainty and value orientation of members will also interact with feedback and have effect on cooperation

Key words: resource dilemma, value orientation, cooperative behavior, cross stage evolvement