The invention discloses a method for preventing an electrochromism product from skip plating and hard spots. The method comprises the steps of oil removing, coarsening, recovering, reducing at two times, activating with palladium, peptizing, plating of chemical nickel, copper pre-plating, copper plating, activating with acid, semi-bright nickel plating, bright nickel plating, nickel sealing, chromium plating, reducing, ultraviolet sterilizing, wind shearing, and drying, wherein washing is performed between every adjacent two processes; when activating with palladium, palladium activating liquid with high tin concentration or palladium activating liquid with low tin concentration is added to a palladium activating bath to control the concentration of tin ions to be 1.2 to 1.8g/L. The invention also provides a method for controlling the concentration of tin ions in the electroplating process. The method is characterized in that two kinds of palladium activating liquid are utilized for effectively adjusting to control the tin ion concentration to be within the optimal range of 1.2 to 1.8g/L, additionally, the content of palladium can also be supplemented, and thus the activating with palladium is effectively promoted, and as a result, the electroplating quality of the product is ensured, and the product is also prevented from skip plating and hard spots.