The　effects　of　pH　value　of　the　precipitating　solutions　on　the　phase　structure,　chemical　components,　and　grain　morphologies　of　PSN　powders　were　investigated.　It　is　found　that　the　metal　ions　of　Nb,　Sc,　and　Pb　will　orderly　precipitate　with　the　increased　pH　value　from　2　to　12　when　using　NH4OH　as　the　precipitant.　When　the　pH　value　reached　8-10,　the　precipitation　rates　of　all　the　three　elements　are　over　99%.　Moreover　the　powders,　which　precipitated　with　pH　value　higher　than　8,　will　undergo　the　crystal　phase　transition　from　pyrochlore　to　pure　perovskite　when　calcined　at　different　temperatures.　On　the　contrary,　the　powders　preparing　at　the　relative　lower　pH　value　always　have　a　certain　quantities　of　pyrochlore　phase.　The　grain　morphology　altered　from　200　nm　ball-like　to　1　gm　sheet-like　with　the　increased　pH　value.　Relaxor　ferroelectric　lead　scandium　niobate　(Pb(Sc1/2Nb1/2)O-3),　which　presents　a　composition　near　to　the　chemical　stoichiometry,　has　been　gained　after　800　degrees　C　calcination　of　the　precipitates　at　a　mild　precipitation　condition　of　pH　value　around　8.　And　the　dielectric　behaviors　of　PSN　ceramics　exhibit　typical　relaxor　ferroelectrics　characteristics.