The invention relates to the technical field of PCB (printed circuit board) plating, in particular to a copper plating solution for PCB through holes and PCB blind holes, and a preparation method and a plating method of the copper plating solution. Each liter of the copper plating solution comprises the following components according to contents: 100-250g of copper sulfate pentahydrate, 100-200g of sulfuric acid, 30-100ppm of chlorine ions, 5-50g of brightener, 3-30g of carrier, 2-20g of leveling agent and the balance of deionized water, wherein the concentration ratio of the copper sulfate pentahydrate to the sulfuric acid is (1-1.25) : 1. The plating method comprises the following steps: putting a PCB with through holes and blind holes into a plating bath with the copper plating solution; plating during air agitation to obtain a copper plating layer. The copper plating layer formed by the plating method has a good deep plating capability as high as 92% above, has a hole-filling rate as high as 96% above, and is dense, smooth, relatively good in malleability, good in gloss, high in toughness and low in internal stress.