Aiming at the problem of insufficient security of traditional cross-domain key agreement protocol, a new cross-domain quantum key agreement protocol is proposed. In the certificateless key negotiation system, the combination of quantum key negotiation and classical cryptographic algorithm is adopted to improve the ability of the protocol to adapt to the existing communication network architecture. The key negotiation process uses three-particle quantum teleportation, and the quantum state non-cloning theorem can guarantee the security of the key during the negotiation process. Compared with other schemes, the proposed protocol has higher quantum bit efficiency and can resist various internal and external attacks such as man-in-the-middle attacks and replay attacks.