Microwave photonics is an inter-disciplinary field that studies the interaction between microwave and photonics for applications such as radar, sensors and telecommunication networks. The unique capabilities offered by photonics for processing ultra-wideband and high-frequency signals make it possible to have functions in microwave systems that are complex or even not directly possible in the radiofrequency domain. It has attracted great interest from both the research community and the commercial sector over the past 40 years and is set to have a bright future. We invite researchers in this field and related ones to contribute original research articles and review articles to this special issue on Microwave Photonics in Chinese Optics Letters.