The invention discloses a continuous variable quantum secret key distribution method for achieving one-dimensional modulation. The distribution method comprises the steps that a signal light field passes through a first amplitude modulator and a first signal adjusting device and then is transmitted to an optical fiber combiner with a reference light field in a sending terminal and is transmitted to a receiving terminal through a quantum transmission channel; first modulation voltage is produced through a first data processing device and is loaded on the first amplitude modulator; in the receiving terminal, quantum signals are separated through a second signal adjusting device and the optical fiber combiner; the separated reference light field passes through a third signal adjusting device and a phase modulator and then is transmitted to a measurement device with the separated signal light field; feedback voltage and a second modulation voltage are produced through a second data processing device and are loaded on the phase modulator to lock relative phases of the signal light field and the reference light field. Modulation and phase locking of signal amplitude can be completed by arranging pair of amplitude modulators and the phase modulator, a device structure can be simplified, and the production cost can be reduced.