The invention discloses a method for measuring the spherical particle spectrum complex refractive index with the single-frequency modulation laser irradiation technology and belongs to the technical field of particle optical characteristic measurement. The method solves the problems that an existing method for measuring the spherical particle spectrum complex refractive index is complicated in measuring process and low in accuracy. According to the method, by establishing a solving model of a forward problem and an inverse problem for measuring a frequency domain reflected signal and a frequency domain transmission signal of a spherical particle system, a particle size analyzer is used for measuring the particle size distribution condition of the particle system, finally, the spectrum complex refractive index of particles is obtained by combining the inverse problem solving technology based on the signals; under the premise that other physical parameters of the particles are known, a frequency domain irradiation transmission model is combined, the Mie theory is used, the particle swarm optimization algorithm is combined, and therefore the spherical particle spectrum complex refractive index is obtained in an inverting mode. The method for measuring the spherical particle spectrum complex refractive index with the single-frequency modulation laser irradiation technology is suitable for measuring the spectrum complex refractive index of the particles.