The invention discloses a backstage design method for the same registered user and multiple departments of an Internet trading platform, including a user server, a demander client, a supplier client, a transaction platform server, and a database. The user server includes a computer, The mobile phone, the platform server is connected with the database and the user's computer and mobile phone with two-way signals, and the input terminals of the computer and mobile phone servers are connected with the output terminals of the registration module. The background design method of the same registered user and multiple departments of the Internet trading platform will change the original trading platform’s single mode of only accommodating applicants, and increase the integration of sales, procurement, finance, and warehouses for the same registered user. The various departments of registered users can coordinate and coordinate the operation and management business online on the same platform, which greatly improves the overall operational efficiency among various departments of users, greatly reduces the rejection of corporate users from using the Internet and reduces the need for users to operate both online and offline. distressed.