For inadequate research on the internal formation mechanism of random group requirements in mobile social network, this paper analyzes the identification progress of random group requirements based on their shared resources and information of group requirements. According to the perception of the requirements and resources of the individuals, we analyze the internal structure of requirements and divide them into four states: state of feasibility, state of unfeasibility with lack of resource, state of unfeasibility with lack of awareness and state of complete unfeasibility. The mechanisms of transition between different states are described. Based on this, this paper analyzes the influence mechanism of random group members忆dynamic changes on group requirements in mobile social networks, and identifies the group requirement that can realize the real-time optimal allocation of group resources. Finally, an example is given to verify the effectiveness of this method.