Assessing the Signal-to-Noise Ratio Variability (SNR) of Landsat 8 Satellite OLI Images is crucial for ensuring the continuity of Landsat satellite data and expanding the application of long-term satellite data in various fields such as ecology, natural resources, and land use. This study is to calculate the SNR of Landsat 8 OLI images from 2014 to 2020, and to evaluate the change of SNR over the past seven years. The technique process is listed as follows: (1)The homogenous areas and the corresponding images are selected from the global areas in a variety of surface types including desert or Gobi, ocean, lakes, snow, and dense vegetation.(2)The mean and standard deviation of the homogenous areas are calculated using the Digital Number images. The SNR is calculated by the ratio between the mean and standard annually. (3) The change of the SNR from 2014 to 2020 is quantitatively analyzed, and the trend of SNR is evaluated. The results show that: The SNR of OLI images in each band remains at a certain level, meeting the requirements for global land surface change studies. Nevertheless, the SNR shows fluctuation change with a small amplitude over the past seven years. The SNR of OLI images in 2014 is the highest while that in 2020 is the lowest. The SNR of OLI images over the past seven years shows a potential downward trend. The results are of significance to the application on the analysis of global change using OLI images.