HALE(high-altitude long-endurance) solar-powered aircrafts are the research frontiers, they can staying airborne for several months, and can form new application ability named "long-endurance+station-keeping". The three-stage development process of HALE solar-powered aircrafts was systematically summarized, including early exploration stage, rapid development stage and operational capability demonstration stage, and typical development plans aboard were introduced. Key technology challenges were analyzed, including aerodynamic configuration design, energy storage battery, high altitude propulsion, large scale structure and flight control, and the suggestions for research directions were proposed. All those can provide reference for innovation development of HALE solar-powered aircrafts.