Abstract: A processing system and a method therefor are provided. The method includes receiving a selection signal that a payment on delivery linked with a mobile application is designated as a payment mode for goods, from a terminal of a user, in which the mobile application is installed, generating an order request signal as a payment server which connects with the terminal over a network matches goods identification data associated with the goods with user identification data of the user who is registered in the mobile application to correspond to each other; verifying ordered records associated with the user identification data and starting a payment session for payment as the terminal executes the mobile application according to an operation of the user who receives the goods, and receiving a payment completion signal generated from the payment session and paying for the goods according to the goods identification data.