The　one-to-one　alternating　droplet　generation　(OOAG)　in　a　double　microfluidic　T-junction　is　a　newly-developing　method　to　construct　droplet　reactors.　However,　little　attention　was　paid　to　its　precise　control,　especially　at　low　interfacial　tension.　This　work　filled　in　the　gap　through　the　experimental　and　theoretical　exploration.　Four　fluid　systems　were　adopted　to　make　the　research　conclusions　more　general.　The　mechanism　of　flow-patten　transition　was　analyzed　to　establish　a　predictive　model　describing　the　operation　window　of　OOAG.　Interface　dynamics　analysis　suggested　that　independent　of　the　proportion　of　continuous-phase,　the　droplet　formation　was　suppressed　and　accelerated　by　the　opposite　dispersed　phase　at　the　earlier　and　later　stages,　respectively.　Additionally,　the　opposite　dispersed　phase　delayed　the　droplet　breakup　at　low　proportion　of　continuous　phase　through　the　interface　deformation.　A　predictive　model　for　droplet　size　was　established　by　considering　the　mutual　effect　of　the　two　dispersed　phases　and　the　fluid　properties.