This paper introduces the principle of digital waveform generator and design a digital function generator based on direct digital synthesizer (DDS) technology used FPGA and necessary analog circuits. By serial communication, the singlechip microcomputer is used to set the frequency and amplitude, as well as the choice ofwaveform; FPGA to change the word of DDS frequency control and to realize the waveform table’s generation; The profile data which FPGA produces is sent into AD7524 to carry on the analogtodigital conversion; The latter level uses the low pass filter and the OCL amplifier to improve the wave quality and to enhance its ability to take the load. At last, the paper gives a frequency analysis between the sine wave produced by the circuit in this paper and the sine wave produced by a signal generator.