Continuous-variable quantum key distribution (CVQKD) is a promosing technology, which can share theoretical unconditionally secure key between Alice and Bob. In particular,CVQKD with the Gaussian- modulated coherent states (GMCS)is one representative scheme, which has been fully proven to be secure against general attack. Over the past years, the GMCSCVQKDscheme has been experimentally implemented by many research groups in laboratories and in field environments.However, in a practicalCVQKDsystem, there are some direct or indirect imperfections that deviates from the assumption in security proofs, which can open security loopholes for Eve to hide himself to successfully steal information about the secret key. Although quantum hacking attacks seriously affect the practical security of CVQKD systems, these attacks have been effectively resisted. These studies promote the commercial applications of CVQKD. In this work, we clearly show different quantum hacking attacks and corresponding countermeasures in hardware of system, i.e., information source, sink,andquantumchannel. Moreover, a brief prospection is given for the study of practical security ofCVQKD.
