A　novel　micro-electromechanical　resonator　based　on　in-plane　mode　was　presented　for　the　measurements　of　fluid　density　and　viscosity.　With　the　purpose　of　enhancing　the　quality　factor　of　micro　resonator,　double　vibrators　were　connected　by　a　center　beam　to　not　only　drive　the　resonant　structure　in　in-plane　vibration　mode　but　also　reduce　the　vibration　stress　to　be　concentrated　in　the　fixed　terminal.　Finite　element　analysis　and　numerical　simulation　were　conducted　to　analyze　and　optimize　the　resonator　structure.　Based　on　the　simulated　analysis,　its　quality　factor　reached　highly　to　96　in　ethanol　with　the　resonant　frequency　of　approximately　34　kHz.　And　the　stress　amplitude　up　to　MPa　on　the　center　beam　had　strong　relationship　with　both　of　the　fluid　characteristics　and　output　voltage,　which　benefited　to　improve　the　measurement　accuracy　of　fluid　density　and　viscosity　based　on　the　piezoresistive　principle.　©　2019　IEEE.