Abstract: Linear randomization pre-processing framework was presented to design feasible physical layer secure transmission schemes. The framework show that, based on characteristic differentiae of wireless channels, additive and multiplicative randomization modules with suitable design would create channel advantage for legitimate users. In the view point of information theory security, the optimal distributions of the additive randomization weights and the multiplicative randomization weights to induce the lowest information leakage to the eavesdropper were verified. Finally, A random sub-carrier referencing security scheme was proposed as an instantiation analysis for the optimization design of multiplicative randomization weights.