We propose a novel scheme for continuous variable quantum key distribution(CV-QKD) using the subcarrier multiplexing technique which was employed in microwave photonics. This scheme allows to distribute N channels independent Gaussian modulated CV-QKD in parallel with one laser source and several phase modulators. We analyze the influence of nonlinear signal mixing and the security in the asymptotic limit. Results indicate that by using this multiplexing technique, each channel will be

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... d a non-Gaussian extra source noise, resulting slightly short of the maximum transmission distance, while the total secret key rate can be considerably increased. This scheme could also be used for key distribution for multi-users and combined with the WDM devices it has the potential to construct a CV-QKD network.