The invention discloses a polishing solution for printed circuit microsections and a preparation method thereof, belonging to the technical field of printed circuit board manufacture. The polishing solution is used for polishing the printed circuit board microsections, and is suitable for observational studies of polishing copper, nickel and other coatings fixed by using crystal glue. The polishing solution comprises alumina powder, gallic acid(3,4,5-trihydroxybenzoic acid) and organic solvents. The polishing solution has the characteristics of simple preparation process, low price, and long time stable storage. The microsections polished by the polishing solution have smooth surface and are convenient for observation.