Method for transforming existing hexavalent chromium plating solution into new trivalent chromium plating solution

The invention discloses a method for transforming an existing hexavalent chromium plating solution into a new trivalent chromium plating solution and belongs to the technical field of electroplating. The method comprises the two steps that firstly, under the conditions that the pH value of the existing hexavalent chromium plating solution is 0.5-1.0 and the temperature is 80-90 DEG C, a specified amount of a reducing agent and a specified amount of the organic acid complexing agent are added, and heat preservation is conducted for two to four hours, so that hexavalent chromium is reduced to trivalent chromium and the trivalent chromium and an organic acid complexing agent form a trivalent chromium active ligand basic solution with the ligand structure being [CrLx.(H2O)6-x]; and secondly, the trivalent chromium active ligand basic solution is adjusted to become the new trivalent chromium plating solution by adding conducting salts and a catalyzer into the trivalent chromium active ligand basic solution formed