When　a　gold　colloidal　suspension　is　subjected　to　ac　electric　field,　＂gold　pearl　chains＂　will　form　due　to　the　dielectrophoretic　(DEP)　force.　Our　latest　experiments　show　that　the　formation　rate　of　gold　pearl　chains,　which　tends　to　zero　at　high　and　low　frequency　limits　and　has　a　maximum　at　a　narrow　mid　range　of　frequency,　is　dependent　on　the　applied　field　frequency.　This　letter　analyzes　the　frequency-dependent　DEP　manipulation　of　gold　colloid　suspensions　using　the　protoplast　model.　Simulated　results　show　that　the　relationship　curve　between　the　frequency　of　applied　field　and　the　velocity　of　gold　colloids　motion　due　to　DEP　agrees　with　our　experimental　observations.　In　addition,　the　orders　of　magnitude　of　the　velocity　due　to　various　effects　in　our　experimental　system,　such　as　DEP　force,　Brownian　motion,　gravity,　and　fluid　flows　induced　by　electric　field,　were　also　estimated.　The　result　implies　that　the　DEP-based　manipulation　of　less　than　2　nm　gold　colloids　is　extremely　difficult　to　be　controlled.　©　2006　IEEE.