Abstract: The present invention is to provide a method for protecting online transaction safety between buyers and sellers, wherein, when a third-party server receives a good transaction information (including a first account information, a first good code and a selling price) from a first terminal device (seller), the third-party server sends the first good code to a verification unit to verify whether a good corresponding to the first good code has been used. If no, the first good code is locked. Then, the third-party server displays the good transaction information on a transaction platform and, when receiving a good purchasing message (including a second account information and the first good code) from a second terminal device (buyer) through the transaction platform, the third-party server deducts the selling price from the money corresponding to the second account information and adds the same to the money corresponding to the first account information accordingly.