A system for securely entering particular information includes a mobile device and a background server. The mobile device includes a first area which is a non-secure environment, a second area which is a secure environment and a switching module implementing switchings between the first and second areas. At least one first application module for executing a business function application is provided in the first area. A second application module for executing a particular information entering application and an encryption module for encrypting entered particular information are provided in the second area. If a particular information entering is required by the first application module, the switching module triggers the second application module to perform the particular information entering, and returns, to the first application module, an encryption result obtained by encrypting the entered particular information. The background server includes an authentication module for authenticating the encryption result.