Media education in Hong Kong was only launched after 1997. Its rapid growth was largely due to the worsening of the media environment and deteriorating of the public sphere after the handover. Media educationists propose to adopt the "social participatory model" to promote media education, to nurture citizens' critical thinking ability, to improve the media environment, and to boost the public sphere. This article discusses the relationship among media education, public sphere and critical citizenship. It also examines the actual practice of the "social participatory model." Findings show that media education in Hong Kong is successful in training citizens' critical mindedness. But due to the apolitical nature of Hong Kong's education environment, media education curriculum tends to be apolitical as well. As a result, media education can only limit its scope in the socio-cultural arena in terms of promoting social participation. The political aspect is often neglected. This is why media education cannot promote the public sphere in Hong Kong to the fullest extent.