With the rapid growth in the number of new media platforms in China, a large number of Internet users have been turned into citizen journalism accounts. With the digital transformation of official media, many citizen journalism accounts are often pulled into news production by official media to co-produce content. On the Chinese Internet, citizen journalism not only plays the role of challenging and influencing agenda-setting and public opinion, but also takes on the task of propagating ideology and values. This thesis explored this phenomenon of journalistic practice by using generic news frames and propaganda theories as theoretical foundations. Meanwhile, this study used mainly quantitative content analysis as research method, exploring the characteristics of news videos produced by Chinese citizen journalism accounts in collaboration with official media, and what propaganda techniques were used to help legitimize authoritarian rule. This study examined 432 collaborative videos on bilibili published by CCTV between 2020 and 2023. The findings suggest that collaborative videos tend to produce soft news with positive human interest and morality frames, while negative news mainly targets foreign countries' conflicts. Furthermore, collaborative videos mainly use soft propaganda and public opinion guidance to disseminate values and ideologies that are in line with the national interest and lead the audience to support the CPC and the government's political governance, which legitimizes authoritarian rule. These results illustrate how Chinese citizen journalism in the propaganda field contributes to the propaganda strategy of the party and the government, how it has been used to legitimize authoritarian rule, and why its characteristics are significantly different from those of the Western scholars.