In order to reduce the non-linear influence of MZM on the analog signa l,a signal transmission scheme based on the RoF system with triangular waves as the subcarrier is proposed.This scheme uses triangular waves with high lineari ty to carry baseband data and modulated by MZM.The modulated optical signal can be directly detected at the receiver of the RoF system to obtain a cosine RF si gnal,which has almost no sideband components caused by the nonlinear modulation of MZM.The simulation analyzes the performance of the triangular subcarrier el ectro-optical modulation scheme under the conditions of direct modulation and i n direct modulation; and compares the direct modulation-triangular subcarrier mod u lation scheme with the traditional single-sideband modulation under the same pa r ameters.The simulation results show that the triangular subcarrier modulation s cheme has a BER of 10－8.4 after 100kilometers transmission without relay under the premise of dispersion compensation,which is 4times lower than the BER of t he single sideband modulation scheme under the same parameters.