Contract signing is an important cryptographic primitive and has many applications in e-commerce. Over last few years, quantum contract signing has attracted much attention because its security is based on the fundamental principles of quantum mechanics. In this paper, a new fair and optimistic contract signing protocol based on quantum cryptography is proposed. Compared with the prior work, this protocol no longer needs to sign the exchanged messages containing the contract, the identifier number of qubits’ sequence and so on, and therefore it does not depend on the current signing technology any longer. Furthermore, the communication complexity is reduced due to removing the exchange of the signatures between two clients.