Mn-doped SiC magnetic thin films prepared by co-deposited molecular beam epitaxy (MBE) method on Si (111) substrates at 950 ℃ have been investigated by reflection high energy diffraction (RHEED), X-ray diffraction (XRD) and X-ray absorption near edge structure (XANES) techniques. RHEED results reveal that the SiC thin films doped with Mn are of the cubic structure. XRD and XANES results show that in the thin films with Mn doping concentrations of 0.5％ and 18％ , almost all the Mn atoms react with Si atoms, forming Mn4Si7 compound embedded in the SiC matrix, and no substitutional or interstitial Mn atoms exist in the SiC lattice. Furthermore, we hold that the ferromagnetism of the Mn doped SiC thin films originates mainly from the Mn4Si7 secondary phase.