The invention discloses a payment system and a payment method based on a USSD (Unstructured Supplementary Service Data) communication protocol, wherein the payment system comprises a system master station, a mobile terminal, a user terminal and an operator terminal, the user terminal is used for initiating a charge request to the system master station through network communication, the system master station is used for receiving the charge request initiated by the user terminal, an App which is capable of communicating with the system master station and has a USSD dialing function is installedon the mobile terminal, the mobile terminal is used for performing USSD dialing after obtaining a charge task, performing transfer charge to the operator terminal through the USSD protocol, and monitoring a charge result and returning the charge result to the system master station; and the system master station is used for generating a charge TOKEN code according to the charge result returned from the mobile terminal and returning the charge TOKEN code to the user terminal. Through adoption of the application scheme of the payment system, the mobile terminal is used as a service terminal, thereby facilitating achievement of complicated business, and also providing an integration scheme for an API (Application Programming Interface) interface.