High-performance plasma discharge is a basic operation mode for the future tokamak fusion reactor. The real-time injection of lithium is an effective way to suppress impurity radiation and recycling, thereby maintaining steady-state control of high-confinement plasma discharge. The Experimental Advanced Superconducting Tokamak (EAST) is the first tokamak to achieve high-confinement plasma discharge over 100 s using real-time lithium injection. Green lithium line was clearly observed during this discharge.