This　paper　analyzes　the　fundamental　mechanisms　in　driving　Au　Pearl　Chain　Formation　(PCF)　based　on　dielectrophoresis　(DEP)　force.　From　experimental　results,　the　PCF　process　strongly　depends　on　the　voltage　and　the　frequency　applied　on　electrodes,　but　weakly　on　the　sizes　of　particles,　which　appears　to　be　contrary　to　theoretical　expectations.　To　explain　the　above　phenomenon,　we　estimated　the　DEP　force　and　the　Brownian　motion　imposed　on　the　Au　nanoparticles,　and　then　investigated　the　AC　electro-osmosis　force　and　the　electro-thermal　force　which　may　possibly　affect　the　PCF　rate.　Numerical　modeling　to　compare　the　forces　is　presented.　By　matching　experimental　and　numerical　results,　we　validate　the　scaling　laws　of　the　DEP　force　and　electro-mechanics　in　the　PCF　of　Au　nano-particles.　©　2007　IEEE.