In this study, the technological status and development trend of time grating displacement sensors are outlined considering from three aspects. Additionally, the sensors' four performance features and recent developments in four technological application areas are described. Subsequently, the evolution process for three generations of time grating sensors is summarized, and three cardinal classes and four categories of the current field-type time grating sensors are introduced, in addition to discussing their relationship with traditional displacement sensors. Moreover, the possible mechanism for next-generation time grating sensors is logically deducted and analyzed. Finally, three characteristics of the extension of the time-space coordinate transformation theory are explored.