The disclosed online transaction method and system uses payment platform acting as an intermediary agent between the merchant and the shipping company to handle the payment. While the payment platform receives payment from the shipping company, the merchant receives payment from the payment platform. The method and system do not require buyers to use the payment method provided by an intermediary transaction platform to make a payment. Instead, the buyer may pay directly to the shipping company. Unlike conventional transaction method based on COD, however, the disclosed online transaction method and system centrally manage a logistics platform or multiple logistics operations run by logistics companies. The merchant does not receive the payment from the logistics company, but rather receive the payment from a centralized payment platform to ensure secure and fast payment.