In　order　to　solve　the　conventional　quasi-Z-source　inverter＇s　defects　including　small　boost　factor,　limited　boost　capacity　and　high　voltage　stress　on　power　transistor　at　low　input　voltage,　a　three-phase　voltage-fed　quasi-Z-source　photovoltaic　grid-connected　inverter　with　high　boost　capacity　is　presented　in　this　paper.　And　the　influence　of　system　dynamic　performance　and　modulation　strategy　on　impedance　network　parameter　is　detailed　analyzed.　On　the　one　hand,　the　smaller　inductance　and　larger　capacitance　of　impedance　network　are　better　for　the　dynamic　performance　through　the　zero　pole　map　of　capacitor　voltage　close　loop,　and　that　is　verified　by　load　changed　transient　simulation.　On　the　other　hand,　the　values　of　inductance　and　capacitance　of　impedance　network　are　different　under　different　modulation　strategies.