The utility model discloses a telescopic entrance to a cave protector, including first reinforcing bar ladder, second reinforcing bar ladder, spacing piece and foraminiferous steel sheet, first reinforcing bar ladder between by the square steel lateral wall of two parallels overlap joint transverse reinforcement a form, second reinforcing bar ladder is formed by overlap joint transverse reinforcement b between two channel steel top surfaces that the notch is relative, the square steel of first reinforcing bar ladder inserts the interior horizontal sliding of channel steel of second reinforcing bar ladder, the end that inserts of first reinforcing bar ladder sets up L shaped steel piece, the inner wall of second reinforcing bar ladder sets up the spacing piece that prevents the terraced L shaped steel piece of first reinforcing bar to be pulled out, spacing piece prevents the slippage of first reinforcing bar ladder, the ladder feet of first reinforcing bar ladder and second reinforcing bar ladder sets up foraminiferous steel sheet, gather materials on the spot, the equipment is fast, high durability and convenient use, low cost, no taste and high economic benefits, can repeated turnover use, the regulation length and can stretch out and draw back.