A method and a system for generating single-sideband Raman light for cold atom interferometer through phase modulation are provided. The system includes a laser, an electro-optic modulator (EOM), a local microwave oscillator, a narrow-bandwidth optical-fiber filter, an optical-fiber power amplifier and a frequency doubling crystal. The laser has frequency of ω and is input to the EOM. The local microwave oscillator applies a modulation voltage with frequency of δ to the EOM and generate double-sideband frequency-modulated light with frequencies of ω±nδ(n=0,1,2, . . . ). This light is filtered by the narrow-bandwidth optical-fiber filter, which outputs the target frequency light and is successively input to the optical-fiber power amplifier and the frequency doubling crystal and yields the single-sideband Raman light for cold atom interferometer. The Raman light generation system has simple structure, low-cost, high integration level, easy implementation, high maturity and good stability, and has practical significance in realizing an engineering-based laser system for high-precision atom interferometer measurement.