The invention discloses a large-capacity data downloading method based on mobile cloud computing and a system thereof. After a downloading request from a mobile device is received by a mobile agent terminal, a multi-threading technology is adopted to parallelly download a file, and file downloading is completed in a short time, and the file is saved in the local of the mobile agent terminal; the mobile device is then informed that the file is already downloaded, and the mobile device then builds network connection with the mobile agent terminal. As the mobile device and the mobile agent terminal are in the same local area network environment, the transmission speed between the mobile device and the mobile agent terminal is quick, and the mobile device downloads the file from the mobile agent terminal through a high-speed network bandwidth.