A system for calculating trace lengths of a PCB layout includes a computer (10) and a database (11). The computer includes: an object setting module (100) for setting objects to define section rules; a section rule defining module (101) for selecting objects as a start point and an end point for each section in a section rule, and defining a length for the section; a trace selecting module (102) for selecting traces from a trace class; a trace calculating module (103) for calculating all lengths of sections contained in each selected trace and a total length of the selected trace, and determining whether all the selected traces have been calculated; an information generating module (104) for generating corresponding notices if necessary; a storing module (105) for storing the section rules and calculation results; and a calculation result converting module (106) for converting the calculation results into a designated data file.