The embodiment of the invention provides an ordering method and device based on two-dimension code and a door control system. The ordering method comprises the following steps: transmitting collected identity information to an identity authentication server and transmitting ordering demands for goods to a system platform by a terminal; verifying identity information by the identity authentication server; generating orders and sending the orders to the terminal by the system platform according to ordering demands when identity authentication is successful; transmitting goods use passwords to the terminal through two-dimension codes by the system platform after receiving order payment completion information; scanning and analyzing two-dimension codes on the terminal by password authentication equipment so as to obtain use passwords, and if use passwords are correct, judging that the authentication is successful. According to the embodiment of the invention, a user can order rooms and the like through the terminal and obtain two-dimension codes which are sent by a merchant and used as passwords, and when checking into a hotel, the user can directly reach the ordered room to unlock the door control system by the two-dimension codes without assistance of a customer assistant. Compared with the prior art, the ordering method provided by the invention has the advantages that higher safety is realized by taking the two-dimension code as passwords and the whole ordering process is more convenient and rapid.