Recent progress in researches on tropical cyclone (TC) intensity and structure changes is reviewed. According to the maximum potential intensity (MPI) theory, at the given thermodynamic state of the atmosphere and ocean, there exists MPI. In fact, tropical cyclones' maximum intensity is generally less than that of MPI theory. There are many internal and external dynamic factors to prohibit TC intensification through structure changes. The changes of intensity and structure involve complex different-scale interactions. The recent researches show that the mesoscale processes resulting in TC asymmetry are crucial to the variation of both intensities and structures of TCs, including vortex Rossby waves, spiral rainbands, mesoscale vortices, environmental flow, and boundary layer processes. The external environment flow also influences the intensities and structures of TCs through these mesoscale processes over the eyewalls