The invention discloses a multi-pore powder spraying device for pretreatment. The device comprises a main spray nozzle; an allocation cavity is formed outside the main spray nozzle and is hemispherical; powder spraying pipes are evenly arranged on the cavity wall of the allocation cavity in the horizontal direction; the interior of the allocation cavity further comprises a rotating body; the rotating body comprises a pair of linearly-arranged blades; a rolling bearing is arranged between the blades and rotates around a supporting arm of the blades; and the supporting arm of the blades is fixed to the bottom of the allocation cavity. The multi-pore powder spraying device for pretreatment has the beneficial effects that perpendicular spraying and blowing of an existing single pipe are changed to inclined side spraying and blowing of multiple pipes, a single reaction region is changed into multiple reaction regions, the reaction area is increased, a desulphurization reaction region is added, and the desulphurization reaction concentration of unit space is reduced; and therefore the purposes of reducing spraying splashing, increasing the desulphurization rate, increasing the powder spraying speed and decreasing the powder using amount are achieved. Besides, because of the arrangement of the rotating body, it can be guaranteed that peristalsis of molten iron is caused once pressure of the powder spraying pipes changes a little, the reaction area is increased, and the reaction efficiency is improved.