The invention discloses an Internet of Things transaction system achieving automatic vending. The system is composed of a vending machine with built-in various commodities and a built-in background service terminal, wherein commodity data information sent by a user is induced, received and sent to the background service terminal by the vending machine, and a returned command from the background service terminal is received by the vending machine to control the opening and closing of a door lock of the vending machine; the background service terminal is used for receiving the commodity data information sent by the vending machine, and conducting comparative analysis of the commodity data information sent by the vending machine and the preset commodity data information, and if the match is right, an opening command is sent to the vending machine; if the match is wrong, an opening-refusing command is sent to the vending machine. Compared with the prior art, by means of the Internet of Things transaction system achieving automatic vending, commodity circulation links are reduced, cold fresh products in dense communities are more applicable, intelligence and automation of the commodity vending are achieved, and the 24-hour uninterrupted vending mode is achieved, consumers can select and buy commodities at any time, the richer and more active consumption experience is provided for the consumers.