Novel　compartment　microparticles　prepared　with　double　emulsion　droplets　as　templates　provide　a　protected　internal　space　for　material　encapsulation.　The　effect　of　three-phase　flow　rate　on　the　micro-droplet　generation　of　double　emulsion　mechanism　is　available　for　reference　to　produce　precise　size　and　highly　monodisperse　particles.　The　influence　of　three-phase　flow　rate　on　the　formation　mode　and　size　of　the　emulsion　droplets　is　investigated　by　combination　of　experiment　and　numerical　simulation.　The　size　of　compound　droplets　decreases　and　frequency　increases　with　the　increasing　outer　fluid　flow　rate.　The　monodispersity　of　the　double　emulsion　reduces　due　to　transition　from　dripping　to　narrowing　jetting　regime.　Outer　droplet　size　increases　with　the　increasing　flow　rate　of　the　middle　fluid,　whereas　inner　droplet　size　is　the　opposite.　The　frequency　increases　and　then　stabilizes,　which　leads　to　a　widening　regime.　When　Q2/Q1　＞　6,　the　multi-core　type　double　emulsion　droplets　are　produced.　Droplet　coalescence　occurs　when　surfactants　is　not　involved.　As　Q1　increases,　there　is　an　increasing　tendency　for　inner　drop　size.　The　outer　drop　size　is　proportional　to　the　sum　of　the　inner　and　middle　flow　rate,　and　that　is　irrelevant　to　Q1/Q2.　For　drop　size,　the　ratio　of　core-shell　and　internal　structure　is　precisely　controlled　by　adjusting　three-phase　flow　rate　respectively.　©　2018　Changchun　Institute　of　Applied　Chemistry,　Chinese　Academy　of　Sciences