An embodiment of the invention discloses a body area network main key generation method. A body area network includes a center node and at least one goal node, the method includes the following steps: the center node receives a first public key of the goal node, and generates a first key variable value based on the first public key and a second public key of the goal node and a first private key and a second private key of the center node, so as to obtain a main key; and the target node receives a first public key of the center node, and generates a second key variable value based on a first public key and a second public of the center node and a second private key and a second private key of the goal node, so as to obtain a main key. The first key variable value and the second key variable value are the same. The body area network key generation method provided by the embodiment solves the problem that a Diffie-Hellman key exchange protocol based on an elliptic curve cannot resist an intermediary, thereby improving security of information transmission.