The invention provides a method for accurately characterizing combined chloride ion content in cement paste under different carbonization degrees. After extensive experimental research and theoreticaldeduction, it is found, based on the titration of a silver nitrate solution, that it is more accurate to determine the content of combined chloride ions by using the supernate obtained by sufficiently contacting the pre-carbonized hardened cement slurry powder with the chloride ion solution to reach adsorption equilibrium and further performing high-speed centrifugation. Since the content of freechloride ions can be accurately determined in the chemical titration, while the specific total content of chloride ions cannot be accurately determined, the content of the combined chloride ions in the cement slurry under different carbonization degrees can be accurately obtained by measuring the concentration of the free chloride ions in the solution after a certain concentration of sodium chloride solution and the cement slurry powder with different carbonization degrees fully contact the to achieve adsorption equilibrium through the silver nitrate titration, obtaining the difference between the precise concentration of the free chloride ions in the initial sodium chloride solution and the final concentration of the chloride ions, and converting the difference to the content of the combined chloride ions.