The invention discloses a refund data processing method applied to a point-of-sale terminal and correlated systems. The method comprises: according to a refund request message sent by a first commercial tenant, a front-end system of a point-of-sale terminal determines a second commercial tenant corresponding to an original transaction correlated to the refund request message; the front-end system of the point-of-sale terminal sends a transaction message carrying the information of the second commercial tenant and the information of the original transaction to a bank account system to carry out account processing; and the front-end system of the point-of-sale terminal receives a response message returned by the bank account system and sends the response message to the first commercial tenant. Therefore, real-time cross-area refund processing can be realized, so that the labor cost and time cost are reduced and the client experience is improved.