A program is developed to draw the isolines of meteorological element fields automatically by connecting discrete points into irregular triangle grids that conform to Delaunay features. The resulting isolines conform to the principles of isoline drawing by hand. The meteorological fields of Shandong Province and the sea surface temperature field of the North Pacific are drawn by the program, which include coastlines and color-filled areas. Through a user-defined coordinate system, it can switch between screen and actual coordinates and realize map projection, etc. The program has good drawing capability, can draw vector graphics, insert and revise the graphics, and set up the display order and Alpha mixing-transparence display. The graphics achieved the vector zoom without grades.