The utility model provides an application writing auxiliary device. The device comprises a demonstration board, a comment board, a writing board, a bottom board and a support. The bottom of the demonstration board is connected with the writing board through a hinge. The demonstration board and the writing board can be folded; the right side of the demonstration board is provided with a comment board. A demonstration paper fixing clamp is arranged in the middle of the left side of the front surface of the demonstration board; a comment paper fixing clamp is arranged in the middle of the right side of the front of the comment board; a writing paper fixing clamp is arranged in the middle of the left side of the front of the writing board; a groove is formed in the front upper part; pens can be placed in the grooves; obliquely placed mobile phone, one end of the bottom plate is connected with the bottom of the demonstration plate through a rotating shaft. The support is of a U-shaped structure and comprises two longitudinal rods and a transverse rod, the two ends of each longitudinal rod are connected with the two sides of the demonstration board through rotating shafts respectively, the transverse rod is arranged on the bottom board, a plurality of embedding grooves are formed in the two ends of the bottom board at equal intervals, and the transverse rod is embedded in the embedding grooves, so that the angle of the demonstration board is adjustable.