Abstract: A key distribution method is provided. The method is adapted for a network. The network comprises a plurality of nodes. In the key distribution method, a plurality of keys are provided to each node. A plurality of blocks are provided, serving as platforms. An algorithmic parameter is selected and a plurality of key parameters are provided to establish a balanced incomplete block (BIB) design area. One of the nodes broadcasts key parameters. The method can reduce the number of the key transmission, fast establish common keys, and reduce the network bandwidth for distributing the keys.