The invention relates to a safe protecting device for high-latitude work of a steel structure and belongs to the field of buildings. The safe protecting device is provided with a steel wire rope and is characterized in that snap rings are fixed at two ends of the steel wire rope and the middle of the steel wire rope at intervals, wherein each snap ring is fixed in a U-shaped groove in the upper end of a corresponding support seat through a pin rod; the support seat comprises the U-shaped groove, a movable clamping plate seat, a blot, a fixed clamping plate seat and a support rod; the lower end of the support rod is fixed on the fixed clamping plate seat; the U-shaped groove is fixed at the upper end of the support rod; a strip groove is formed in the fixed clamping plate seat; the lower end of the bolt is connected with the movable clamping plate; the upper end of the bolt penetrates through the strip groove and is screwed with the nut; the movable clamping plate seat and one end of the fixed clamping plate seat take the shape of a bent hook shape; and the movable clamping plate seat and a bent hook at the end part of the fixed clamping plate seat are clamped on a top flange of a steel beam.