The minerals identification and component retrieval obtained from reflectance spectrum of lunar samples were greatly affected by the environment of lunar surface, and had been applied to approximately 5% of the lunar surface where lunar soil was immature. In contrast, the emission spectrum of lunar samples which is mainly composed of silicate minerals not only had obvious spectral characteristics, but also had little influence by the lunar’s atmosphere, temperature difference and vacuum. Thus a new approach to study the component and physical properties of lunar surface was offered. In the future, the emission spectrum of lunar samples collected by Chang’e 5 detector can be used to extract the compositional analysis of silicate minerals which are the main components of lunar crust. And it is important supplement to visible-near infrared spectrum in remote sensing study. However, the greatest challenge in the laboratory emissivity measurement is finding out the best measuring methods and instruments in order to obtain accurate and reliable spectrum data. In this study, using TurboFT 102F and Bruker VERTEX 70V, based on fourier infrared spectroscopy method, independent blackbody method and reflectivity method, the emission spectrums of simulated lunar soil were measured under natural laboratory, the nitrogen cold background and vacuum environment. The numerical accuracy of emissivity spectrums was analyzed and evaluated using the error propagation law or the thermal infrared emissivity spectra of Apollo samples. The study found that the reflectivity emission spectral characteristics were the most obvious and reflectivity emissivity spectral values in which measurement accuracy was the highest in the three emission spectrum measurement methods. Thus reflectivity method under sealed laboratory environment is the best choice for lunar sample emission spectrum measurement now before the simulate lunar vacuum environment is built. We hope that research and analysis results of the paper can provide a theoretical basis and technical reference for emissivity spectrum measurement of Chang’e 5 sample.