GaAs-based triple-junction solar cell has high photoelectric conversion efficiency and is the main material of satellite solar arrays. The scattering spectrum characteristics can be used to assist in determining the solar arrays’ attitudes and satellite working status, which have great significance for space object identification. An automatic scattering spectrum measurement system of space object’s surface materials was established and the scattering spectrum of solar cell samples was measured. The measurement system primarily consists of REFLET 180S and FieldSpec@4 fiber spectrometer. The REFLET 180S can provide a dark environment, a stable light source with spectral range of 400~1 800 nm and a high-precision turntable with 0.01°angular resolution. FieldSpec@4 spectrometer has an advantage of high spectral resolution (3 nm @700 nm, 10 nm @1 400/2 100 nm). According to the strong specular reflection characteristic of the solar cell samples, a standard plane reflector was selected as the calibrator. The incident angles were 5°, 15°, 30°, 45° and 60°, and the reflection angles were plus or minus 2°in the direction of specular reflection with 0.1° angle intervals. The measurement results showed that there were three obvious absorption peaks in the visible (600~900 nm) scattering spectrum of the GaAs-based solar cell, and theses absorption peaks appeared to the left “migration” characteristic with the increase of incident angles, and in the near-infrared (900~1 800 nm) scattering spectrum showed distinct periodic oscillation characteristics. While the scattering spectrum of Si-base solar cell did not have these characteristics. The structure of GaAs-based solar cell was complex, and its physical structure was simplified into a double anti-reflection coating layer and three semiconductor absorptive dielectric layers: a top cell called GaInP layer, a middle cell called GaAs layer, and a substrate cell called Ge layer. Based on the thin-film interference theory, the scattering spectrum of GaAs-based triple-junction solar cell was modeled by the equivalent optical admittance method. The simulation spectrum basically fitted the absorption characteristics in the visible band and the periodic oscillation characteristics in the near-infrared band, which indicated the correctness of the spectral reflectance model established by thin-film interference theory. The influence of different film layers on the scattering spectrum of GaAs-based triple-junction solar cell was analyzed by using the spectral simulation model. The simulation results showed that the main function of the DAR layer was to reduce the spectral reflectance, which had little effect on the shape of the spectral curve. The main function of the Ge layer was to increase the light transmittance and absorption efficiency, which had no effect on the scattering spectrum. GaInP and GaAs layers played a major role in the spectral shape of GaAs-based triple-junction solar cell. GaAs layer was the main reason for the interference characteristics of the scattering spectrum in the near-infrared band. GaInP layer had the main influence on the absorption characteristics in the visible band, and it also modulated the amplitude and frequency of the interference curve in the near-infrared band. The research results can provide data support for satellite solar panel and solar cell debris identification.