The dynamics of urban innovation capacity remain to be clarified, and this study combines the ‘Buzz-and-Pipeline’ model with dual innovation theory to explain urban innovation capacity. Specifically, from the two dimensions of spatial scale and knowledge type, "inter-city—explicit knowledge" and "intra-city—tacit knowledge" were used to define Buzz and Pipeline, respectively. Then, this study meticulously classifies urban innovation capabilities into two categories: incremental and breakthrough innovation. Further, this study focuses on how the knowledge interaction in the ‘Buzz-and-Pipeline’ framework drives urban dual innovation (incremental innovation, breakthrough innovation). An empirical study was conducted with the China's biomedical industry and the results showed that: Buzz and Pipeline have different mechanisms for the city's dual innovation capabilities. Both Buzz and Pipeline and their interaction have a positive impact on city's incremental innovation capacity. Both Buzz and Pipeline have an inverted U-shaped effect on city's breakthrough innovation, and their interaction has a negative impact. This study provides some insights into differentiated strategies for fostering incremental and breakthrough innovation capabilities in cities in developing countries.