The system is designed to construct an Arbitrary Waveform Generator based on DDFS,with a PLL4046 and FPGA as the key,complimented by necessary analog circuit,so the system is very simple and convenience to realize.In the design ,there are four main module.The first module is oscillator,the modules are responsible for the formation of oscillogram and prefer waveform to output,in other words it can form square waveform,sinusoid waveform and delta waveform and output one kind waveform or the linear combination of several kind waveform;so this module is the key of the system.we use FPGA to realize this module,because FPGA have enough speed and logic unit to use ,and because of its programmable attribute,we can write procedure to complete our design,it is very convenience and reliable.The second module is the control of frequency.in this module,PLL(Phase Lock Loop)4046 plays a key role,iwhich realioze the change of frequency.In fact this module is also the key of the system,if there is not this module ,the frequency of the system can’t be changed and the frequency of waveform can’t be changed,too.PLL4046 have many function,for example:multiply frequency ,modulation.now we use it to multiply frequency,so the range of system frequency is very wide and having high definition.The third module is the digital-to-analog module.Obviously,it change the digital signal which is from the output port of FPGA into analogy signal by DAC0832,at the same time amplifer is used to amplify analogy signal and control of its amplitude range. The last module is demonstration module,its duty is to display the frequency of waveform.Then,by cascading every module,this system is realized. At last,this system can form square waveform,sinusoid waveform and delta waveform and linear combination of them.The frequency can be adjusted from 100Hz to 15KHz,its interval is 100Hz.It can gratify the request of the design.