The invention discloses a quantum key distribution system, which comprises a distribution terminal, a master station service system, a quantum key mobile storage device and a quantum key distributionnetwork. The master station service system applies a quantum key to the quantum key distribution network in response to a quantum key application request of the distribution terminal. The quantum keydistribution network transmits a pair of quantum keys to the first quantum key downloading interface and the second quantum key downloading interface according to the application of the master stationservice system. The master station service system obtains the applied quantum key from the first quantum key downloading interface; The distribution terminal obtains a quantum key corresponding to the quantum key applied by the master station service system from the second quantum key downloading interface through the quantum key mobile storage device. The system can realize the low cost, large-scale and flexible distribution of quantum keys in distribution terminals through mobile storage devices. A quantum key distribution method is also disclosed.