Unlocking system of portable electronic device and method

The invention relates to an unlocking system of a portable electronic device. The portable electronic device is provided with an altimeter. The system comprises a setting module, an acquisition module, a completion judgment module, an unlocking judgment module and an unlocking module, wherein the setting module is used for presetting a height variation value and a preset period for unlocking operation; the acquisition module is used for acquiring the sensed initial height of the portable electronic device and a height variation value relative to the initial height and storing the initial height and the height variation value into a memory; when the stored height variation value changes within the preset period, the completion judgment module shows that movement is being carried out, otherwise, the movement is completed; the unlocking judgment module is used for comparing the stored height variation value and the preset height variation value for the unlocking operation, unlocking conditions are satisfied for