Narrow-disperse　poly　(styrene-co-n-butyl　acrylate)　(P　(St-co-nBA))　microspheres　were　prepared　by　dispersion　copolymerization　in　a　mixture　medium　of　ethanol　with　water　initiated　by　2,　2＇-azobisisobutyronitrile　(AIBN)　using　poly　(N-vinylpyrrolidone)　(PVP)　as　a　steric　stabilizer.　Products　were　characterized　by　(1)H　nuclear　magnetic　resonance　((1)H-NMR),　differential　scanning　calorimetry　(DSC),　Fourier　transfer　infrared　spectroscopy　(FTIR),　scanning　electron　microscopy　(SEM)　and　laser　particle　size　analysis　(LS).　The　influences　of　comonomer　ratio　of　nBA　to　St　(nBA/St),　polymerization　temperature,　stabilizer　content,　media　polarity　and　initiator　concentration　on　particle　size,　size　distribution　and　monomer　conversion　were　examined.　Results　showed　that　with　increasing　molar　ratio　nBA/St,　the　particle　size　increased,　but　the　size　distribution　broadened,　and　the　monomer　conversion　decreased　slightly,　when　the　ratio　nBA/St　exceeded　20/80　it　decreased　rapidly.　As　the　polymerization　temperature　increased　from　60　degrees　C　to　75　degrees　C,　the　monomer　conversion　and　the　particle　size　all　increased,　but　the　size　distribution　broadened.　When　the　temperature　rised　to　80　degrees　C　the　particles　had　a　tendency　of　merging　with　each　other,　at　the　same　time　the　monomer　conversion　rate　decreased.　The　content　of　stabilizer　had　no　obvious　effect　on　the　monomer　conversion　rate,　but　the　average　size　of　particles　decreased　and　the　size　distribution　of　particles　narrowed　with　increasing　the　stabilizer　content.　The　particle　size　and　polydispersity　initially　decreased　with　the　increase　of　EtOH/H(2)O　ratio,　passed　through　a　minimum,　and　then　increased.　When　EtOH/H(2)O　mass　ratio　was　80/20　similar　to　90/10,　the　size　distribution　of　particles　was　narrow.　With　the　increasing　of　initiator　concentration,　the　monomer　conversion　rate　and　the　particle　size　increased,　while　the　size　distribution　broadened.　At　a　well-controlled　condition,　the　narrow-disperse　particles　in　the　size　range　of　0.7　similar　to　2　mu　m　were　achieved.　The　SEM　images　indicated　the　copolymer　particles　were　smooth　on　their　spherical　surface.　The　(1)H-NMR　and　FTIR　spectra　confirmed　the　polymerization　between　St　and　nBA.　DSC　experiments　showed　the　glass　transition　temperature　(T(g))　of　the　copolymers　in　the　range　of　56.7　similar　to　107.1　degrees　C.　The　copolymer＇s　composition　and　it＇s　T(g)　could　be　controlled　by　the　ratio　of　the　comonomers.