The invention discloses a system and method for remote data secure backup, which are characterized in that both a data center and a backup center comprise database servers for storing data and quantumVPNs; the data center further comprises a quantum key sending module; the backup center further comprises a quantum key receiving module; the quantum key sending module is used for generating local light and signal light which accords with a CV-QKD protocol; the local light and the signal light sequentially enters a single mode optical fiber in mutually perpendicular polarization directions and are transmitted to the quantum key receiving module; and the quantum key receiving module is used for carrying out polarization compensation on a received light signal, enabling the local light and thesignal light to be recovered to be in the mutually perpendicular polarization directions, then carrying out synchronous regulation on the local light and the signal light and finally carrying out detection on a quadrature component of a light field of the signal light. The system and method have the advantages that the CV-QKD protocol is combined with the VPNs, so that security of remote backup data is improved; and the system and the method are more applicable to a long-distance remote data backup scene.