The strong localized field in micro-nano photonic structures brings new opportunities for the study of the light-matter interaction. By designing optical modes in these structures, photons and excitons in micro-nanostructures can exchange energy reversibly or irreversibly. In this paper, a series of our recent studies on the strong and weak photon-emitter coupling in micro-nano structures especially in plasmonic and their coupled structures are reviewed, such as the principle of efficient, tunable and directional single photon emission, and engineering the electromagnetic vacuum for enhancing the coupling between photon and exciton. These results provide new physical contents for the light-matter interactions on micro and nanoscale, and have potential applications in the on-chip quantum information process and the construction of scalable quantum networks.