The invention discloses a light steel protecting window. The window comprises a protecting window body, a telescopic sun shield, hooks, a hanging rod, an outer guardrail plate and sliding blocks, thefront plane of the protecting window body is provided with a window, a notch is formed in the corresponding rear plane of the window, the telescopic sun shield is arranged at the upper end of the rearplane notch of the protecting window body through screws, the hooks are arranged on the two sides of the lower end of the telescopic sun shield, handrails of the two sides of the protecting window protection are telescopic rods, the outer guardrail plate is arranged at the protecting window body rear plane notch, and is fastened with the handrails of the two sides in a welding mode, the hanging rod is arranged between the telescopic sun shield and the upper plane of the outer guardrail plate, sliding grooves are formed in the inner sides of the telescopic rods at the upper ends of the handrails at the two sides of the protecting window body, the sliding blocks are matched with the sliding grooves, and a push rod is used for connecting the left side sliding block with the right sliding block. According to the light steel protecting window, the outer guardrail plate can freely move back and forth through a main telescopic rod, the forward extending distance of the protecting window is increased, the space is conveniently and reasonably utilized, and the window is simple in structure and convenient to use.