A functional material—composite structural magnetic core is the magnetic core mainly consisting of magnetic material and having regular geometric form. It includes a box with a slot cavity and through hole. The inner magnetic core is installed inside the cavity of the box. It is characterized by: there are multiple inter-layers inside of the cavity of the slot. The inter-layers divide the slot cavity into the multiple continued ring slot and inside the ring slot many inner magnetic cores are installed respectively. The advantages are: wide application frequency band, large application temperature range, expanded electromagnetic compatibility. The continued stability and sudden change of the electromagnetic characteristics can meet requirements of the electronic technology. The sensing and sending of power transferred signal and control of noise wave etc. showed its composite excellent performance, corresponding and matching characteristics.