Summary: A chaos-based arbitrated quantum signature (AQS) scheme is designed on the basis of an improved quantum chaotic encryption algorithm whose security is ensured due to the implementation of the quantum one-time pad that embraces the key-dependent chaotic operation string. It involves in a small-scale quantum computation network with three participants in three phases, i.e. initializing phase, signing phase and verifying phase. The signatory signs the encrypted message and then the receiver verifies the signature is valid with the aid of an arbitrator who plays a crucial role when a dispute arises. Analysis shows that the signature can neither be forged nor disavowed by the malicious attackers.