The invention discloses a fire-proof smoke-exhausting-type variable cross-shaped shunting regulation four-way device and a dust retention-prevention processing method. The variable cross-shaped shunting regulation four-way device comprises a lower bottom plate, an upper top plate and side surfaces; the lower bottom plate is divided into a high-dust particle concentration area, a middle-dust particle concentration area and a low-dust particle concentration area; and the high-dust particle concentration area and the low-dust particle concentration area are made of dust retention-prevention materials with different rough heights. According to the cross-shaped shunting regulation four-way device, clean materials with different rough heights are adopted at parts with different dust-retention concentrations, so that retention of suspended particles at the cross-shaped shunting regulation four-way device can be effectively reduced; and meanwhile, the use amount of the abrasion-resistance materials is reduced, so that the cost of the cross-shaped shunting regulation four-way device is lowered.