The invention discloses a PM2.5 purification nano purification agent for a protection mask and an application of the nano purification agent, wherein the nano purification agent comprises the following components in parts by mass: 18-25 parts of titanium dioxide, 10-15 parts of sodium percarbonate, 2-6 parts of tourmaline, 7-9 parts of glycerol and 75-90 parts of distilled water. The nano purification agent is wide in application and can be conveniently embedded into a mask body by taking sponge, cotton yarn, silk and the like as a carrier, the carrier can be conveniently cut and the thickness of the carrier can be conveniently adjusted according to the masks with different specifications, the nano purification agent has an excellent oxidation decomposition purification effect, does not cause any damage to a human body, and is safe and convenient to use; the combination of the titanium dioxide and the sodium percarbonate can efficiently oxidize and decompose the PM2.5; and the preparation cost of the nano purification agent is low, the effect is good, and the nano purification agent has extremely high market application values.