In this paper, we demonstrate a prototype of magnetic tunable bandstop filter by using magnetic multilayers of [FeGaB 25 nm/Al2O3 5 nm]4 prepared by magnetron sputtering. The multilayer structure exhibits a relatively low coercive field and RF loss compared to the single layer film with the same thickness. By placing a single transmission line on the top of magnetic multilayers, a prototype of tunable bandstop filter was fabricated and operates from 4.5 GHz to 7.08 GHz under very low magnetic bias fields from 100 Oe to 400 Oe. These low loss multilayer films are good candidates for RF/microwave applications.