A firmware update method and a system using the same are provided. The firmware update system comprises a device, a storage unit comprising a boot block code, and a network interface controller. When the system boots, the device executes the boot clock code, and determines whether an update alert exists. When the system boots, the network interface controller connects to a web server via Internet, downloads firmware from the web server, and generates the update alert after the firmware is downloaded. In response to the update alert, the device selects the firmware to be updated as an active code to the storage unit. The systems reboots after the firmware is updated to the device.