Abstract: A method for distributed key management in wireless Ad Hoc network is developed based on mobile agent.Moving in the network,mobile agents exchange information with the nodes and other agents to build the global matrix information which includes the secret key of nodes according to a policy. When a new node want to join the Ad Hoc network,other nodes will authenticate the new node with its secret key and other k-1 secret key of other nodes.The nodes can exchange the global information and secret key with few agents rapidly.The problem with big network load,long service time and low success ratio in former distributed authenticate algorithm can be solved in this way.This approach reduces the system overhead and it is very efficient and robust to transfer packets.