Abstract: Multi-agent system is increasingly becoming a powerful paradigm for modeling and developing large, complex and distributed information systems. The mechanism of dynamic role assignment is often required to be supported in many systems developed by using the technology of multi-agent system. The influence caused by the constraints among goals to role assignment is not considered in the known algorithms of dynamic role assignment from the current literatures. The model of dynamic role assignment for multi-agent system with parallel constraints among goals is firstly proposed. Multi-role assignment manager agents are especially introduced to take the computational task of role assignment jointly in order to avoid the computational bottleneck caused by a single role assignment manager agent. Then, the algorithm of goal partition is presented based on the goal structure diagram with parallel constraints. Finally, the algorithm of role assignment is given and the time complexity is analyzed. The run time of the algorithm of role assignment is experimentally investigated. And it is shown that the theoretic result is consistent with the experimental result. This goal partition in the model assures that the computational results produced by multi-role assignment manager agents can be directly incorporated without checking parallel constraints.