For the purpose of probing into why there is an enormous cognitive bias amongst Mainland China citizens and Hong Kong citizens. This study used quantitative content analysis as the research tool to figure out how mainstream media outlets in Mainland China and Hong Kong frame Hong Kong protest events since the British sovereignty transfer in 1997. This paper selected three significant Hong Kong protest events as empirical cases, 1 July protest (2003), Occupy Central movement (2014), Anti-Extradition Bill movement (2019) to find out the transformation between two media outlets, Xinhua News and South China Morning Post. Framing theory, as the conceptual framework is applied to analyze all selected textual contents in this study. The result of this analysis presents two different versions of media report towards the same issues by two media outlets. And also, the research results also detect a subtle transformation of media coverage in three protest events. Eventually, the paper provides some thinking about media coverage and Hong Kong protest. Keywords: Hong Kong, media coverage, social protest, media, internal security