Abstract: Quantum key distribution is the most secure technology to distribute a secret key. There is a set of orthogonal product states in a two-qubit three-state quantum system which can show nonlocality. This paper provides a quantum key distribution protocol based otn the nonlocality of such system. The two parties establish the key by exchanging quantum qubits and performing the collective measurement on them. The laws of quantum mechanics guarantee that this protocol is unconditionally secure. No other people can get the key without being found. There are no entangled states and quantum operations needed in the protocol. So it is easier to carry out in practice. And it can gain high reliability and robustness.