Abstract: This invention relates to a method used to zoom in selective plot area in display, which method is inserted an inserted box into the display screen of a display device, and said inserted box can be removed to said display screen anywhere and the plot covered within said inserted box can be zoomed in according to predetermined zoom rate or zoom rate immediately set. Said method of this invention is applicable to a plotting calculator so that by way of keying in the keys of said plotting calculator the user can precisely and quickly select the plot area going to zoom in display.