The invention discloses a generation method and device of a numerical control program for steel plate gas cutting, and relates to the field of welding and cutting. The generation method comprises the steps that a computer acquires hole coordinates and vertex coordinates obtained by scanning a sample plate through a digitizer and sends the hole coordinates and the vertex coordinates to numerical control plate punching equipment, and the numerical control plate punching equipment automatically generates a hole-forming numerical control program; a first application program calls a CAD program, and the CAD program automatically reads the hole-forming numerical control program and automatically generates a sample plate outline drawing in a CAD format; a second application program automatically reads the sample plate outline drawing in a CAD format, acquires the coordinate data on the sample plate outline drawing and sends the coordinate data to FastCAM; the FastCAM automatically generates the numerical control program for steel plate gas cutting according to a numerical control program template for steel plate gas cutting and the coordinate data. The generation method and device are suitable for generating the numerical control program for steel plate gas cutting. By means of the generation method and device, outline drawings of a large number of sample plates can be rapidly converted into CAD drawings, numerical control programs can be rapidly generated, and working efficiency can be improved.