Numerical　simulation　on　two-phase　flow　characteristics　at　convection　microfluidic　Y-junctions　based　on　the　two-phase　flow　interface　tracking　method.　It　is　found　that　the　Y-angle　of　the　microfluidic　Y-junctions,　capillary　number　of　continuous　phase,　and　the　flux　of　two　phases　have　a　great　influence　on　droplet　generation　time,　rate　and　size.　The　decreasing　of　continuous　phase　capillary　number　and　Y-angle　results　in　the　increasing　of　the　droplet　volume.　At　the　same　time,　with　the　increasing　of　flux　ratio　of　the　dispersed　phase　and　continuous　phase,　the　influence　on　the　droplet　volume　is　becoming　smaller.　But　the　flow　flux　ratio　cannot　infinite　increase　or　decrease.　Because　the　dispersed　phase　can　only　takes　the　form　of　liquid　column　or　silk　and　it　unable　to　generate　the　droplet　when　the　ratio　is　greater　than　0.5　or　no　more　than　0.05.　When　the　dispersed　phase　flux　is　increasing,　the　corresponding　droplet　formation　rate　is　almost　proportional　increasing;　the　influence　of　the　dispersed　phase　flow　on　the　length　of　the　droplets　evolution　is　greater　than　the　continuous　phase.　In　addition,　in　the　formation　process　of　droplet,　the　filling　time　becomes　longer　and　the　necking　time　becomes　shorter　with　the　increasing　of　the　Y-angle.　The　droplet　detachment　mechanism　is　mainly　under　the　effect　of　normal　stress　of　the　continuous　phase.　©　2014　Journal　of　Mechanical　Engineering.