A method for controlling a wearable device includes the steps of: providing the wearable device which includes a sensor; detecting and recording movement data relative to the wearable device via the sensor; determining whether the wearable device has triggered a start condition; if the start condition has been triggered, analyzing the movement data; determining whether a user has finished putting on the wearable device according to the analyzed movement data; and if the user has finished putting on the wearable device, determining whether the wearable device is worn on a left side or a right side of the user according to the analyzed movement data.