The　ex　situ　MgB2/Fe　mono-filamentary　tapes　have　been　prepared　by　powder　in　tube　(PIT)　technique　starting　from　MgB2　powders　with　different　sizes.　The　critical　current　densities,　J(c),　of　the　tapes　have　been　measured　at　various　magnetic　fields　and　different　temperatures.　It　was　found　that　the　anisotropy　of　J(c)　is　influenced　significantly　by　the　starting　MgB2　powder　grain　size.　The　recrystallized　grain　size　of　the　annealed　MgB2　Core　is　increased　with　increasing　of　starting　powder　size.　XRD　analysis　of　the　MgB2　filaments　removing　the　Fe　sheath　showed　that　it　existed　slight　stronger　texture　at　the　interface　between　MgB2/Fe　sheath　than　that　in　the　centre　of　the　MgB2　filaments.　The　correlation　among　the　starting　powder　size,　texture　and　anisotropy　of　J(c)　was　discussed.