An accounting method and system are provided, in which a service flow management (SFM) module receives application layer content information sent from an application function (AF) entity, and then sends the application layer content information to an accounting unit; then, the accounting unit performs accounting according to the application layer content information and a predefined accounting policy. A corresponding accounting system is further provided, in which the transmission of the application layer content information is implemented by adding an accounting extension parameter into a message for saving the application layer content information. Through the invention, the particular content information of the application layer service is reported to the accounting server to perform the different accounting depending upon the content of the application layer service effectively. Additionally, the invention is easily implemented, and makes full use of the existing system, and thus, the cost is reduced.