An apparatus for finding a charger based on map constructing, wherein the apparatus is applicable for real-time mapping of an area to be localized in which at least one locating tag is arranged, a charger is located in the area to be localized, and the charger is provided with one locating tag as well, information of each said locating tag comprises unique coding information used for distinguishing an absolute position thereof, the apparatus can be a mobile electronic device, and the apparatus comprises: a locating tag information reading unit, configured to read information of the locating tag; a coordinate system constructing and recording unit, configured to take a location of a first locating tag as a coordinate origin of a coordinate system when information of the first locating tag is obtained by the locating tag information reading unit of the mobile electronic device which is moving along a certain trajectory for a first time, and record the information of the first locating tag and coordinate values thereof; an encoder, configured to record a moving distance and a moving direction of the mobile electronic device relative to a starting point in real time when the mobile electronic device traverses all over the area to be localized with the coordinate origin as the starting point; a first calculating unit, configured to calculate coordinate values of location of other locating tag except the first locating tag each time when the mobile electronic device obtains information of the other locating tag based on a moving direction and a moving distance of the mobile electronic device relative to the starting point during the traversing process, and send the information of the other locating tag and the corresponding coordinate values to the coordinate system constructing and recording unit; a charger position determining unit, configured to determine whether a locating tag is on the charger or not according to the unique coding information of the locating tag every time when the mobile electronic device obtains information of the locating tag, so as to obtain coordinate values of the charger; a wireless receiving/transmitting unit, configured to transmit the coordinate values of the charger to the charger; and a map constructing unit, configured to construct a map according to the information of the locating tag and coordinate values thereof recorded by the coordinate system constructing and recording unit; the wireless receiving/transmitting unit is further configured to receive coordinate values of a shift position of the charger transmitted by the charger which has shifted, and send the coordinate values of the shift position of the charger to the coordinate system constructing and recording unit to update the coordinate values of the charger, so as to cause the map constructing unit to update constructed map. a locating tag information reading unit, configured to read information of the locating tag; a coordinate system constructing and recording unit, configured to take a location of a first locating tag as a coordinate origin of a coordinate system when information of the first locating tag is obtained by the locating tag information reading unit of the mobile electronic device which is moving along a certain trajectory for a first time, and record the information of the first locating tag and coordinate values thereof; an encoder, configured to record a moving distance and a moving direction of the mobile electronic device relative to a starting point in real time when the mobile electronic device traverses all over the area to be localized with the coordinate origin as the starting point; a first calculating unit, configured to calculate coordinate values of location of other locating tag except the first locating tag each time when the mobile electronic device obtains information of the other locating tag based on a moving direction and a moving distance of the mobile electronic device relative to the starting point during the traversing process, and send the information of the other locating tag and the corresponding coordinate values to the coordinate system constructing and recording unit; a charger position determining unit, configured to determine whether a locating tag is on the charger or not according to the unique coding information of the locating tag every time when the mobile electronic device obtains information of the locating tag, so as to obtain coordinate values of the charger; a wireless receiving/transmitting unit, configured to transmit the coordinate values of the charger to the charger; and a map constructing unit, configured to construct a map according to the information of the locating tag and coordinate values thereof recorded by the coordinate system constructing and recording unit; the wireless receiving/transmitting unit is further configured to receive coordinate values of a shift position of the charger transmitted by the charger which has shifted, and send the coordinate values of the shift position of the charger to the coordinate system constructing and recording unit to update the coordinate values of the charger, so as to cause the map constructing unit to update constructed map.