The invention provides a method for switching encryption safety data among peer-to-peer user nodes in a P2P (peer-to-peer) network. Two arbitrary peer-to-peer user nodes in the network, namely, a user node A and a user node B, log in the network to obtain a public key certificate through an authentication server; the user node A has a self-provided random number NA and a random number NB sent from the user node B; the user node B has a self-provided random number NB and a random number NA sent from the user node A; and the encryption algorithm is applied to enable the user node A and the user node B to form an encryption channel for data encryption transmission. In the invention, safety communication can be set simply, the interaction frequency is low, and except the first-time certificate transmitting of explicit message, other information interaction is achieved under the condition of encrypted message, so that a better security is ensured.