In quantum Gaussian key distribution experiment, post-processing is one of key technologies to improve data reconciliation efficiency and guarantee the security of the extracted secret key. A specific data reconciliation of post-processing is proposed through the slice error correction which uses the quasi-cyclic low density parity check code and traditional low density parity check code to cascade to compress and code. To analyze the security of secret key extracted, direct reconciliation and reverse reconciliation scheme are proposed in individual attack and collective attack on the continuous variable quantum key distribution with homodyne detection. The result indicates that the data reconciliation efficiency can achieve 91.2% when code length is 2×10₅ and the third and fourth level code rate is 0.3/0.95. The amount of the extracted secret key can reach 3.98 kbit/s using the optimal attack and transmission distance can reach about 30 km, which proves the safety of the data reconciliation scheme and can satisfy the requirement of the metropolitan area network communication.