The invention provides a building material conveying cutting device. The device comprises a groove, a rectangular block, a port, a protection box, a warning lamp, an electric telescopic rod, a partition block and a second pressing plate; the port is formed in the right end face of a first supporting plate, the rectangular block is assembled on the right end face of the first supporting plate, theleft end of the rectangular block penetrates through the port to extend to the left side of the first supporting plate, the groove is formed in the upper end face of the rectangular block, due to design, the problem that an existing gypsum line coating conveying cutting device cannot conveniently grind a blade is solved, the first supporting plate is assembled on the right side of the lower end face of the protection box, the second supporting plate is assembled on the left side of the lower end face of the protection box, the warning lamp is assembled on the upper end face of the protection box, the electric telescopic rod is assembled on the upper end face in the protection box, a second pressing plate is assembled on the right side of the annular side face of the electric telescopic rod, a spacer block is assembled in the protection box, the second pressing plate is arranged on the upper side of the spacer block, due to design, the aim of protecting a conveying belt is achieved, blade grinding is facilitated, the conveying belt is protected, the function is complete, and safety and reliability are achieved.