Excel? 2003: Tools → Options, select View Page in the pop-up menu, and uncheck the "Grid Line" option.
Excel? 2007 and above:? Select the menu view and uncheck the "Gridlines" option in the "Show/Hide" column.
Take Excel 20 10 as an example to demonstrate:
1, the default display style
2. The effect after unchecking the "Grid Line" option under the "View" menu.