||Protected areas, a globally accepted conservation strategy, play a fundamental role in biodiversity and species conservation. There are increasing concerns about the ecological influence of nighttime light within protected areas due to the emergence of more light-related ecological issues. Previous approaches for detecting nighttime light mainly used the traditional data source released by the Defense Meteorological Satellite Program Operational Linescan System (DMSP/OLS), but its coarse spatial resolution and limited radiometric resolution dramatically hamper prompt detection. In this study, we used data from a new source, the Visible Infrared Imaging Radiometer Suite Day-Night Band (VIIRS DNB) to detect nighttime light disturbance within protected areas of mainland China. Protected areas extracted from Landsat 8 Operational Land Imager and the Thermal Infrared Sensor (OLI-TIRS) images served as ground truths to assess detection accuracy. We found that the VIIRS DNB data provided more and better details compared with the traditional DMSP/OLS data. Pixel-based trend analysis clearly indicated that within the protected areas lighted pixels existed extensively and increased significantly from 2012 to 2017. This study provides a new solution to better understand human activities within protected areas.