The thesis introduces a new structure of Direct Digital-RF Modulator which converts I/Q 8Bit digital signals to RF signals directly. Thermometer decoder converter and 8-Fold Linear Interpolation are used in the new structure. The simulated DSB digital image rejection of above 53.52dB and spur rejection of above 53.01dB is realized.The simulated SSB digital image rejection of above 59.15dB and spur rejection of above 53.92dB is realized.