The invention discloses a space-borne microwave and laser communication link integrating system and an application method. The integrating system comprises a laser, light amplifiers, a convergent lens, a light beam controller, an optical antenna, a photoelectric detector, a microwave/light demodulator, a light/microwave demodulator, a multiplexer, an electricity amplifier and a radio frequency antenna. The application method includes that a digital signal is modulated to a light area via the laser; an optical signal is coupled to the optical antenna for transmitting via light beam coupling; the optical signal is received and coupled to the photoelectric detector by the optical antenna; the optical signal is received by the optical antenna, processed by the light beam controller, coupled to the light/microwave demodulator, and converted into a microwave signal, the microwave signal is amplified by the electricity amplifier and coupled to the radio frequency antenna for transmitting; the microwave signal is received by the radio frequency antenna, amplified by the electricity amplifier and input to the multiplexer to realize microwave signal combination, then is modulated to the light area via the microwave/light demodulator; and finally the combined signal is coupled to the optical antenna for transmitting via the light beam controller. The space-borne microwave and laser communication link integrating system is small in size, low in energy consumption, and can be widely used in military and civil space-borne communication industry.