The invention provides a modulator driving method and system suitable for quantum state random optical signals, and the system comprises: an input end group which comprises at least two input ends, wherein each input end is used for inputting aligned random input signals; an adjustable gain amplifier group which comprises at least two adjustable gain amplifiers; a broadband resistance network terminal for combining the voltage signals output by the adjustable gain amplifiers and outputting a combined signal; a broadband amplifier for amplifying the combined signal to the amplitude required bymodulation to form a driving signal; and a modulator, wherein a signal ground port of the modulator is connected with a power supply, a power supply signal is processed by the modulator and then loaded to the broadband amplifier through the radio frequency port, and the modulator receives a driving signal output by the broadband amplifier from the radio frequency port and modulates the quantum state random optical signal input into the modulator according to the driving signal. According to the invention, broadband driving at the level of 0Hz-10GHz can be satisfied, and the problem of substrate jittering is effectively solved.