Ultrafast Transmission Electron Microscopy (UTEM) integrates high spatial and temporal resolution, making it possible to directly visualize the dynamic processes of materials. This paper mainly introduces the development and application of UTEM system, including: the basic principle of UTEM system based on pump-probe technology; the current UTEM systems in several major institutions around the world; the first generation UTEM system based on thermal emission electron gun and the second generation UTEM system based on field emission electron gun (FEG) independently developed by Li Jianqi's team from Institute of Physics, Chinese Academy of Sciences; the latest research achievements in UTEM system combined with ultrafast real space imaging, ultrafast electron diffraction (UED) and time-resolved electron energy loss spectrum (TREELS), such as lattice and electron dynamics, phase transition dynamics, photon-induced near-field electron microscopy (PINEM), etc. At present, UTEM has become a powerful tool for the study of non-equilibrium dynamics at micro-nano scale. In the future, as electron pulse quality and spatial resolution of TEM continue to improve, UTEM is expected to achieve higher spatial and temporal resolution. China has invested relatively less in the research of UTEM. At present, it is necessary to seize the development opportunity of UTEM, effectively promote the innovation and industrial development of key technologies, core components and major products in the field of UTEM, and closely link scientific and technological innovation with industrial development.