Signal generation with special time domain waveforms is an important research content in the field of microwave photonics and has been widely used in various fields such as military and civilians. This paper briefly introduces several specific optical function waveform generation technology based on frequency-domain synthesis and time-domain synthesis. The advantages and disadvantages of the frequency-domain synthesis and time-domain synthesis are compared and analyzed. At the same time, several introduced technology are compared and summarized from the tuning ability of the waveform repetition frequency, the waveform duty ratio, the multiplication factor, the system application and the system structure of the signal generator.