The disclosure relates to a user information transmission method, device and system, and belongs to the field of electronic technology application. The method comprises the following steps: receiving an acquisition request for requesting acquisition of target user information sent by an application server, wherein the target user information is user information corresponding to a terminal accessing the application server; acquiring the target user information from the user information recorded in a database according to the acquisition request; encrypting the target user information; and transmitting the encrypted target user information to the application server. Through the disclosure, the effect of transmitting the encrypted user information to the application server by a platform server is achieved. The disclosure is applied to transmission of the user information.