The high stable sinusoidal carrier generation technology is the important technology in capacitive displacement sensing task. Whether the capacitive displacement sensing can be realized accurately is directly related to the realization of the core load index of space gravitational wave detection. In the space missions of the gravitational waves,the high stable sinusoidal carrier generation technology based on the important technology of the inertial sensor—high-precision capacitance displacement sensing technology is researched. By improving the factors affecting the waveform stability in direct digital system(DDS), the improved step wave filtering method based on DDS technology is determined as the sinusoidal wave generation method. Through model building and theoretical analysis, the circuit is studied and the sinusoidal wave stability index at normal temperature can reach 21 ppm/Hz without considering the influence of temperature.