The present invention provides a cloud-storage-based file processing method and system. The method includes: a cloud server receiving a trigger request from a mobile terminal and the trigger request is a cloud processing task request triggered by the mobile terminal; the cloud server performing a corresponding processing operation according to the trigger request; and, when the trigger request is an uploading request, selecting a file which needs to be uploaded from the cloud server's cloud storage space and transferring the selected file to a target website. According to the present invention, by using the cloud server on behalf of a user to carry out the file processing operations, such as downloading and uploading, it helps the user completing the online file sharing process, prevents the file uploading and downloading processes from being affected by the network access condition and the mobile terminal's hardware quality, and saves the user the data volume of the mobile terminal throughout the process.