Abstract: The generation of sinusoidal signal with direct digital synthesis (DDS) technology is studied. The spurious signals of DDS generated by phase truncation, amplitude quantization, (D/A) conversion and reference clock are analyzed. The errors caused by phase truncation and amplitude quantization are simulated with Matlab. Simulation results agree with the theoretical values. Meanwhile, a sinusoidal signal source is realized with DDS on field programmable gate array (FPGA). The measured real spectra with spectrum analyzer is given. The result shows that the generation of sinusoidal signal with DDS can achieve good spectra and satisfy the system requirements.