Abstract: In this paper, a technical scheme for the composition identification and source analysis of contaminants deposited on the surface of spacecraft structural panel was formulated. Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) detection technology was used to identify the composition of the white contaminants on the surface of spacecraft structural panel after thermal vacuum test. The results show that the main components of the contaminants are amides. By comparing the ATR-FTIR spectra of suspected contaminants with those of contaminants, it is inferred that the contaminants deposited on the surface of spacecraft structural panel come out of the hot melt adhesive in the inner layer of the heat shrinkable tube during the thermal vacuum test. In addition, the correctness of the inference of contaminant source is proved through a verification test. This study may provide technical support for the prevention and control of spacecraft contaminants.