An online real estate trading system for real estate brokerage period compensation comprises the following elements : a seller smart-terminal to transmit a sale request, real estate information, the desired sale price of real estate when the sale request is received, the real estate information, and the desired sale price from the seller in order to make an online sales contract at the predetermined sale price; a broker smart-terminal to transmit a sale price range and a brokerage period determined through an actual inspection of the seller′ s real estate and consultation with the seller by receiving the sale price range and the brokerage period from a broker, in order to make a real estate brokerage contract online by sending a penalty for the real estate to a predesignated depository account through a bank server, and to receive a purchaser′ s actual survey request for the real estate; a purchaser smart-terminal to receive and display the sale price range and the brokerage period for the seller′ s real estate, to transmit a desired purchase price for the real estate by receiving the desired purchase price from a purchaser, and to make the online sales contract at the predetermined sale price; and a real estate brokerage server to register/notify a real estate sale advertisement of the corresponding real estate by receiving the sale request, the real estate information, and the desired sale price from the seller smart-terminal and to register/notify the sale price range and the brokerage period by receiving the sale price range and the brokerage period from the broker smart terminal.(110) Seller smart terminal(120) Broker smart terminal(130) Purchaser smart terminal(140) Real estate brokerage server(200) Bank serverCOPYRIGHT KIPO 2014