A mathematical model of forming a composite coating on optical fiber was established. The model is based on existing mathematical models for coating optical fibers with polymer coating and experimentally defined rheological behavior of the investigated dispersed system. The model was developed for a dispersed system consisting of poly(ethylene-co-vinyl acetate) - EVA in a form of toluene solution and powders of magnetic materials (BaFe12O19 and SmCo5). The influence of the die diameter, diameter of the original optical fiber, concentration of EVA and magnetic powders on the thickness of composite coating was investigated. The model shows good agreement with experimental data.Postavljen je matematički model formiranja kompozitne prevlake na optičkom vlaknu. Model je zasnovan na postojećim matematičkim modelima prevlačenja vlakana polimernom prevlakom i eksperimentalno utvrđenom reološkom ponašanju ispitivanog dispeznog sistema. Model je razvijen za disperzni sistem koji čine rastvor poli(etilen-ko-vinil acetat) EVA u toluenu i prahovi permanentnih magnetnih materijala (BaFe12O19 i SmCo5). Ispitivan je uticaj prečnika dizne, prečnika osnovnog vlakna, koncentarcije EVA i magnetnih prahova na debljinu kompozitne prevlake. Model pokazuje dobro slaganje sa eksperimentalnim podacima