This thesis presents a method that extracts microstrip lines from the layout of multi-layer microwave passive circuits. After extracting some essential rectangles making up components like capacitors or inductors in the circuit by the algorithm presented previously, we can get the other essential rectangles which could be a part of microstrip lines. When we extract all microstrip lines and construct a connection table to record the components connected to every microstrip line, this program then can determine where the microstrip line should be inserted into the schematic. Finally, a schematic corresponding to the layout will be generated, and then designers can compare this schematic with the original schematic for debugging.