The invention discloses a three-dimensional winding inductor. The three-dimensional winding inductor comprises a PCB, an input bonding pad, an output bonding pad, a plurality of conductive channels and a plurality of inductive coil conducting wires, wherein the PCB is a PCB including dual dielectric layers or multiple dielectric layers; various conductive channels pass through adjacent two dielectric layers or multiple dielectric layers of the PCB; various inductive coil conducting wires are arranged on the same dielectric layer of the PCB; two ends of various inductive coil conducting wires are respectively connected with two conductive channels; furthermore, all the inductive coil conducting wires are divided into more than two layers; all the inductive coil conducting wires are sequentially connected through the corresponding conductive channels; and two ends of all the inductive coil conducting wires sequentially connected through the corresponding conductive channels are electrically connected to the input bonding pad and the output bonding pad respectively. The Q value of the three-dimensional winding inductor is proper; and thus, the three-dimensional winding inductor can satisfy practical engineering use requirements. The invention further discloses an LC filter, a transformer and an equalizer.