Emerging optical devices demand miniaturized, integrated and intelligent optical zoom systems, thus stimulating development in nano-optoelectronics. Metalenses are two-dimensional planar structures with lens function composed of arrays arranged specifically to equally focus wavelengths of light. Due to their ultrathin and lightweight properties and their ease of integration, it is expected that they will revolutionize optics by replacing the conventional bulky, curved lenses used that pervade optical devices. However, once the micro/nano-structures of a metalens are fabricated, their shape and size cannot be modified, which can not realize the real-time adjustment of focusing and will limit the further development of metalenses′ functions and applications. Currently, substantial effort is being devoted to solving this problem. One of the most attractive aspects of metalenses is in the way they combine metasurface lenses with smart materials. In this article, we first provide an overview of novel tunable metalenses. Then, we elaborate and analyze their regulatory principles and device performance, respectively. Finally, we summarize the current problems and difficulties facing the development of tunable metalenses and describe the direction of their future development.