The invention provides a method for preparing a lightning arrester for deeply limiting an operation overvoltage of a UHV (ultra high voltage) system. Multiple groups of lightning arresters are installed on a laid line and comprise lightning arresters at a head end and a tail end of a laid line and lightning arresters at the middle of the laid line. The method has the advantages that the method hasthe potential to reduce overvoltage deeply, the operating overvoltage level in a substation can be significantly reduced, and the method is simple and has low cost compared with other restrictions.