The invention provides a method for eliminating a large fluctuation risk of wind-solar-electricity grid connection. By the characteristic that active power transmitted by an ultra-high voltage DC channel can be controlled through fast adjustment on converters at two ends, the large fluctuation risk for a power grid caused by wide-area wind-solar-electricity grid connection is eliminated through adjusting the transmission power of the ultra-high voltage direct current delivery channel up and down. A power control strategy of eliminating the large fluctuation risk of the wind-solar-electricity grid connection by the ultra-high voltage direct current delivery channel is obtained by calculating the large fluctuation risk quantity R of the wind-solar-electricity grid connection and an adjustable output space of the ultra-high voltage direct current delivery channel on the basis of analysis of the fluctuation condition of the wind-solar-electricity grid connection.