Abstract: Most of the ad hoc network group key management protocols are often improved in some respects at a great cost in other respects, since there is a contradiction between bandwidth and computation resources in ad hoc network. A new distributed group key management protocol is therefore proposed and named TPAN protocol, i.e., a tree-based group key agreement using bilinear pairing for mobile ad hoc networks, which combines the merits of both PSTR and PTGDH together. In TPAN the PSTR key tree is taken as the trunk with the PSTR or PTGDH protocol as branches or sub-trees. The communication costs and calculating costs of different protocols are compared with each other and their security is analyzed, and the results show that the TPAN protocol can achieve the balance between computation costs and communication costs with low costs and security provided.