The present inventions relates a wireless charging coil structure in electronic devices, comprising a PS coil module capable of emitting electromagnetic wave energy and a PR coil module capable of receiving power energy by electromagnetic induction. Each of the PS and PR coil modules includes a bar-shaped magnetic conductor, on which an insulated wire is wound into a first coil that is extended along the magnetic conductor to a given length and wound reversely into a second coil, thus producing an induction coil comprising at least the first and second coils. The induction range with given space formed between the first and second coils is used for electromagnetic induction to transmit signals and power energy. Such structure can be applied not only in planar handheld electronic devices, but also in other wireless power transmission systems that require narrow induction surface for power transmission.