The generation of microwave signals in the optical domain is a hot research topic at present, and it is widely used in communication systems, signal processing, radar and other fields. The frequency and the time domain synthesis methods for generating specific optical pulse signals based on continuous radio frequency modulation and frequency-time mapping technology in the field of microwave photonics are respectively introduced, and several specific schemes of the two methods are introduced in detail. The advantages and disadvantages are analyzed from the aspects of the tuning ability of the pulse repetition frequency, the pulse duty cycle, the pulse type, and the stability of the system structure.