The invention discloses a measurement method and device for holospectrum of an optical waveguide device. The method comprise the following steps: a broadband light source is divided into three light beams, the light beams are transmitted to a to-be-measured optical waveguide, a fixed-optical-distance optical path and a mirror respectively, and two ways of signal light and one way of reference light are obtained; the reference light and the two ways of signal light are subjected to interference, two ways of interference light are obtained and subjected to photovoltaic conversion, and two electric signals are obtained; in a mirror moving process, continuous sampling and AD conversion of the two electric signals are performed, and two groups of data are obtained and subjected to Fourier transform; the amplitude spectrum of the optical waveguide is calculated by means of two amplitudes of Fourier transform, and phase spectrum of the optical waveguide is calculated by means of a real part and an imaginary part of Fourier transform. On the basis of the method, the measurement device for the holospectrum of the optical waveguide device can be constituted by the broadband light source, an optical splitter/combiners, the fixed-optical-distance optical path, the movable mirror, photodetectors, a data acquisition system and a computer. The measurement method and device have the advantages that the interference resistance and precision are high, the amplitude spectrum and the phase spectrum of the optical waveguide can be measured simultaneously and the like.