It　is　very　difficult　to　control　the　measuring　condition　owing　to　the　moisture　absorption　of　ultrafine　powder　at　room　temperature.　In　order　to　overcome　such　disadvantage　that　the　microstructure　of　ultrafine　powder　would　be　changed　in　the　traditional　measuring　method　for　dielectric　property,　a　new　method　preparing　the　organic-inorganic　composite　sample　was　proposed　to　estimate　the　dielectric　properties　of　ultrafine　BaTiO3　powder.　The　composite　samples　were　prepared　by　mixing　ultrafine　BaTiO3　with　epoxy　resin　in　vacuum.　The　temperature　dependence　of　dielectric　permittivity,　dissipation　factor　and　electrical　conductivity　of　the　composite　samples　at　various　frequencies　was　determined.　It　is　suggested　that　based　on　the　theoretical　conversion　of　dielectric　permittivity　and　establishment　of　microstructural　model,　the　dielectric　properties　of　ultrafine　BaTiO3　powder　can　be　estimated.