The invention discloses a material conveying device of a road surface crack sealing machine. The material conveying device comprises a material conveying pipe and a nozzle, wherein the nozzle is connected with one end of the material conveying pipe through a fixing bolt; an outlet end of the nozzle is connected with an ironing plate; the ironing plate is internally provided with a heating pipe; and a clamping groove is formed in the side face of the lower part of the ironing plate. The invention further discloses an application method of the material conveying device of the road surface crack sealing machine. With the adoption of the manner, the material conveying device of the road surface crack sealing machine, provided by the invention, can be used for carrying out secondary heating on sizing materials flowing out from a discharging hole of the nozzle; the quality of the crack sealing sizing materials is guaranteed, and the sizing material can be ironed while flowing so that the crack sealing efficiency is improved; meanwhile, when the method is used for carrying out crack sealing work of the material conveying device of the crack sealing machine, the labor for operation is saved, the crack sealing efficiency is high and repeated procedures are few, so that the labor intensity of operators is effectively alleviated and the material conveying device is worthy of being popularized and applied.