A bicycle electric telescopic apparatus comprises a first tube, a second tube, a positioning structure, an electric positioning actuator, and a power supply. The first tube has a center axis. The second tube is telescopically received in the first tube. The positioning structure is configured to relatively position the first tube and the second tube in a telescopic direction extending along the center axis of the first tube. The electric positioning actuator is configured to actuate the positioning structure. The power supply is configured to be detachably and electrically connected to the electric positioning actuator. The power supply is configured to be detachably and electrically connected to an additional bicycle electric telescopic apparatus.