For the problem that paralleled inverters cannot share reactive power proportional to their power capacity in islanding microgrid. Originally, the effect of inverter output impedance and line impedance to reactive power sharing with conventional droop control is analyzed. Following, a method adjusting the output reactive power by paralleling capacitor at the inverter output is proposed, and the relationship between paralleled capacitors, line impedance and reactive power is analyzed. On the basis, virtual capacitor method is realized to improve reactive power balance. Finally, the proposed method and analysis are verified through simulation.