Abstract: Electron source is the core component of vacuum electronic devices, and on-chip micro-electron source is the key and foundation for realizing miniaturized and on-chip vacuum electronic devices. Silicon oxide Horizontal Tunneling Junction Electron Source (HTJES) is a new type of on-chip miniature electron source developed by our group in recent years, which has the advantages of high emission efficiency, high emission current density, low operating voltage, ability to withstand rough vacuum and fast temporal response, etc., and shows a large potential for applications. In this paper, we will systematically introduce the silicon oxide HTJES from three aspects, including micro-processes and theoretical models of electron emission, arrayed integration, and applications in vacuum electronic devices, and summarize the works done by our group in this field.