Large-scale sustained demonstrations will seriously affect the stability of social order. Since June 2019, Hong Kong's economy has been affected to some extent by the impact of continuous demonstrations on various industries. Rapid and accurate identification of areas affected by demonstrations plays a very important role in loss assessment, economic recovery, and government governance. In this paper, we proposed a novel method to identify the affected areas using night light remote sensing and VGI data. Firstly, we captured the highly overlapping photographs of the study area by a mobile phone on passenger aircraft on August 28, 2019. Following regular photogrammetry steps, night light remote sensing image was generated. Then we compared it with POI density maps and Luojia-01 night light image, and initially marked the affected areas, which were further validated by VGI photos. We finally confirmed two affected areas in Kwun Tong District. A simple quantitative analysis was performed to assess the influence on affected areas. We conclude that the proposed method can quickly identify the areas where economic activities are affected in Hong Kong. Our method can also be used to study economic changes in other cities, which is of great application value in precise urban governance.