If you want to set the background of the pdf file to green, just add a background color to the PDF file. If we want to add a background color to a pdf file, we need the help of a PDF editor. For example, we can use the xunjiepdf editor to open the file, then select the document button, find the background in the document button, and then click the add button. At this time, a menu for adding background settings will pop up, in which we can set the background color of the PDF file to green.