This paper addresses the problem of the voltage sag events’ effect on high-power LED lamps. The LED lamps with high requirements on power quality are susceptible to voltage sag events of the grid. In this paper, the working principle of high-power LED lamps have been analyzed. The voltage sag tolerance characteristic and secondary start-up performance of LED lamps have been tested and analyzed under room temperature and low-temperature conditions respectively. The testing results provide the data support for the design and operation of high-power LED lights for different fields.