A device for delaying dust stratification of a cross of a cooler of a gasification furnace relates to technology for delaying dust stratification of crosses of coolers of gasification furnaces and overcomes shortcomings of other technology. The device is structurally characterized in that a switch two-position valve is mounted on a main gas back blowing pipeline, switch two-position valve upstream stop valves are respectively mounted on the left side and the right side of the switch two-position valve, simultaneously a one-way valve is mounted at one end of the main gas back blowing pipeline, the cross of a cooler of a gasification furnace is further mounted at one end of the main gas back blowing pipeline, a front tee joint and a rear tee joint are respectively mounted at connection positions of the main gas back blowing pipeline with a main and secondary line system, which is formed by connecting pipes, of the switch two-position valve, a secondary flow limiting orifice plate is mounted at the top end of the main and secondary line system, which is formed by connecting pipes, of the switch two-position valve, and a secondary gas back blowing pipeline is mounted on one side of the main and secondary line system, which is formed by connecting pipes, of the switch two-position valve.