The invention relates to a four-state modulation continuous variable quantum key distribution data coordination method and system, and the method comprises the steps: enabling a key to be modulated toa coherent state, and enabling the coherent state to be transmitted to a receiving end through a quantum channel; acquiring a measurement result by utilizing a balance homodyne detector, further acquiring a normalization result of a coherent state, determining a filtering function value, judging whether each bit of key is reserved or not, if so, marking freezing bit information at the position ofthe bit of key, and sending a key information segment in the reserved key to a sending end through a classical channel; Judging whether the quantum channel is safe or not, and sending judgment information to a receiving end; If the judgment information is quantum channel security, freezing bit information of the key information except the key information segment is coded by a system Polar code and then sent to a sending end; And the freezing bit information is decoded by a Polar code of the system, key information corresponding to the freezing bit information is obtained, and a final securitykey is obtained through encryption amplification. According to the method, the data coordination efficiency can be improved, the security key can be effectively extracted, and the equipment complexity can be reduced.