Recognising that the key of the continuous-variable quantum key distribution system is difficult to extract,due to the low efficiency of its data reconciliation,we introduced the PEG (Progressive-edge-growth) algorithm to construct the check matrix of LDPC codes in a given distribution.The simulation results show that LLR-BP decoding on the check matrix constructed by the PEG can reach convergence faster than that on the check matrix constructed by the traditional Mackay method,under a distribution of the same degree.The reconciliation efficiency of the system reaches 934％.The extracted security key amount is 541 kb／s.The transmission distance can reach 445 km.