The invention relates to the technical field of automatic cutting, and discloses an automatic cutting machine and a scribing method thereof. The automatic cutting machine acquires the distance between the pen point of a scribing pen and the surface of a to-be-scribed material; if the distance between the pen point of the scribing pen and the surface of the to-be-scribed material is not in a preset range, up and down position of the scribing pen is adjusted until the distance between the pen point of the scribing pen and the surface of the to-be-scribed material is in the preset range. By controlling the distance between the pen point of the scribing pen and the surface of the to-be-scribed material, excessive contact or separation between the pen point and the to-be-scribed material can be avoided, so that scribing is enabled to be accurate and quick.