The　effective　magnetic　permeability　of　magnetorheological　fluids　(MRF)　is　one　of　its　most　important　material　parameters.　It　determines　the　computational　accuracy　of　many　material　and　mechanical　models　of　MRF.　In　this　study,　a　theoretical　model　applicable　to　the　calculation　of　the　effective　permeability　of　MRF　is　proposed　based　on　the　Maxwell-Garnett　mixing　rule.　The　calculation　method　of　the　average　magnetic　field　of　the　dispersed　phase　and　continuous　phase　in　MRF　was　improved　in　this　model.　The　concept　of　multiple　magnetization　between　adjacent　particles　is　introduced　based　on　the　particle　morphological　characteristics　of　MRF.　To　verify　the　accuracy　of　the　theoretical　model,　a　uniform　magnetic　field　generator　is　built　to　measure　the　effective　permeability　of　MRF　with　different　concentrations.　The　experimental　results　demonstrate　that　the　proposed　model　can　effectively　predict　the　permeability　of　MRF　in　different　magnetic　fields.　The　main　reason　for　the　model　error　is　the　neglect　of　the　variation　in　particle　microstructure.