The invention discloses a preparation method of a lithium-ion battery with a conductive polymer coated positive electrode. The positive electrode sheet is a positive electrode slurry made of a positive electrode material, a conductive agent, a positive electrode binder, a conductive polymer or a conductive polymer monomer, and a solvent. The negative electrode sheet is composed of negative electrode material, thickener, negative electrode binder, and solvent mixed into negative electrode slurry and negative electrode current collector. The specific capacity of the battery is increased by 10-20% by adding a conductive polymer or a conductive polymer monomer to the slurry for coating. The invention effectively improves the performance of the prepared positive electrode material, and because the method is simple, the product cost is reduced, the process is simplified, and the method is suitable for large-scale production.