Low-altitude aircraft are the physical carriers through which the low-altitude economy moves from concept to scaled operation. Taking electric vertical take-off and landing (eVTOL) aircraft as its core object, this paper systematically reviews the research progress and bottlenecks of their key technology system. After briefly tracing the trajectory of technological evolution, the paper analyzes five dimensions: overall aerodynamic configuration, distributed electric propulsion, energy supply and management, intelligent autonomous flight, and low-altitude traffic management. The study finds that tilt configurations account for the highest proportion of global product designs and are gaining relatively unified recognition; the core contradiction of electric propulsion systems is shifting from "whether it can fly" to "the synergistic optimization of power density and thermal management," with high torque density and power density becoming the central pursuit of motor design; the physical constraints on battery energy density persist, and hybrid energy architectures are attracting increasing attention; conflict detection and resolution (CDR) methods can be grouped into two major categories—classical rule-based methods and learning-based methods; and consensus is forming on the status of low-altitude route maps as a new type of public infrastructure. This paper argues that low-altitude aircraft technology is currently in a critical window of transition from prototype validation to airworthiness operations, and that the construction of a system-level safety governance framework will become the core variable determining the scaled deployment of the technology.