The invention discloses a method and a device for filling a continuous casting tundish with argon, and belongs to the technical field of steelmaking and continuous casting. The device for filling the continuous casting tundish with the argon comprises a first closed mechanism, a second closed mechanism and an argon filling pipeline, wherein the first closed mechanism is arranged in the tundish and positioned between a first stick plug hole and a pouring hole of a tundish cover; a plurality of holes are formed in the lower part of the first closed mechanism; the second closed mechanism is arranged in the tundish and positioned between a second stick plug hole and the pouring hole of the tundish cover; a plurality of holes are formed in the lower part of the second closed mechanism; the argon filling pipeline is arranged in the tundish cover; and a plurality of argon blowing openings are formed in the argon filling pipeline. According to the method and the device for filling the continuous casting tundish with the argon, the blowing-in amount of the argon is reduced, the argon filling efficiency is improved, and the intake amount of external air is reduced; and furthermore, the rated aim of reducing secondary oxidization of molten steel is fulfilled, so that the comprehensive control effect for the first slab quality is better.