In the we-media era, short videos are gaining great popularity, which effectively cater to users’ fragmented time for relaxation and entertainment. Short video advertising has become one of the most profitable business models, many KOLs prefer to imbed blurred boundary ads into the videos they create. Yet limited research has explored the effectiveness of blurred boundary ads. Based on persuasive communication theory, we develop a research model to investigate how users respond to blurred boundary ads in short videos. Data has been crawled form short videos including implicit ads. The correlation analysis results indicate that source of information and information dissemination channel positively affect ad recognition, while information quality negatively influences ad recognition. In addition, ad recognition has negative impacts on users’ willingness to forward and purchase. We further divide KOLs into three groups: junior KOLs, waist KOLs, and head KOLs. Statistical results are consistent between the overall users and sub-groups. Implications for theory and practice are discussed.