Swapping billing method, as an important part of operation and management system in charging and swapping station, which seriously affects its commercial operation of charging and swapping station. Aiming at the inaccuracy of the existing methods, we analyze the billing methods and propose a swapping billing method based on charging capacity and apply in heavy-duty truck. It chooses fully charged battery for swapping. It charges the battery replaced from the electric vehicle, after charging is completed, the total charging capacity is obtained according to the charging records, which is taken as battery capacity consumed on the electric vehicle. It calculates the swapping service cost according to the electricity price, and completes the charging of electric vehicle swapping. This paper takes the charging capacity of battery as the billing basis, and the proposed method is simple, reasonable and accurate without extra intelligent devices. The verification results in heavy-duty truck experimental environment demonstrate that the proposed method could calculate the swapping cost precisely, and get better effect in charging and swapping operation system.