The invention provides a method for monitoring illegal relocation of a POS (Point-of-Sale) terminal. The method comprises the following steps that: 1. a POS machine records a time interval value TA from the moment that the dialing is accomplished to the moment that the linkage with a bank transaction platform is established successfully, and uploads the TA to the bank transaction platform through a transaction message; 2. the bank transaction platform receives and stores up the TA; 3. a relocation monitoring system compares the TA with a set reference time value TR, when the difference between the TA and the TR exceeds a preset threshold TH, the POS machine is judged as having illegal relocation, then the relocation monitoring system accounts the transaction situation of the POS machine at regular time so as to make an illegal relocation monitoring report blacklist; and 4. the POS machine is monitored through the monitoring report blacklist. By adoption of the method, probable illegal relocation of payment terminals such as the POS machine and the like can be monitored and found in time, and criminal activities such as that a criminal relocates the POS machine illegally to cash out and the like are prevented effectively.