A notification method includes obtaining, according to period t1, coordinates a1 and a speed v1 of a device after a first geo-fence is set, setting a second geo-fence in response to coordinates a1 being outside the first geo-fence and v1 exceeding a threshold, where the initial radius of the second geo-fence is greater than that of the first geo-fence and a center point of the second geo-fence is the same as that of the first geo-fence, obtaining, according to t1, coordinates a2 and a speed v2 of the device after the second geo-fence is set, adjusting period t1 to a period t2 in response to the coordinates a2 being within the second geo-fence and outside the first geo-fence, obtaining, according to the period t2, coordinates a3 and speed v3 of the portable electronic device, and outputting a notification when the geographical coordinates a3 are located within the first geo-fence.