The invention discloses a 
quantum-key-distribution-network-based mobile 
encryption system and a communication method thereof. The method comprises that: a mobile terminal is registered in a network; the registered mobile terminal is connected with any 
quantum terminal by a key updating interface, and applies for the downloading of shared keys in a certain data volume to the 
quantum terminal; after the mobile terminal downloads the keys, the quantum terminal transmits a quantum centralized control 
station address to the mobile terminal for updating, and the mobile terminal takes a centralized control 
station on the quantum centralized control 
station address as a calling centralized control station; after the calling centralized control station is determined, the mobile terminal submits a 
cipher text to the calling centralized control station; the calling centralized control station re-encrypts the 
cipher text, and transmits the re-encrypted 
cipher text to a called centralized control station; the called centralized control station re-encrypts the cipher text, and transmits the re-encrypted cipher text to a called user; and after the called user decrypts the re-encrypted cipher text to obtain a 
plaintext, the communication is finished. In the method, the 
encryption does not require multiple 
matrix multiplication operations, so the computational load of the 
encryption is greatlyreduced; and simultaneously, the 
key distribution security of the highest level can be ensured in the 
key distribution of a 
quantum key distribution network.