The nonsymmetrical T-source DC-AC inverter (NS-TSI) realizes the functions of DC voltage boost and DC-AC power conversion using single stage configuration. The DC Boost voltage ratio of NS-TSI is much higher than that of conventional T-source inverter (TSI). This merit makes the NS-TSI is more suitable for the photovoltaic and wind grid-connected generation inverter to further extend the power generation range of renewable energy generators and further increase the system utilization efficiency. The principle of NS-TSI is analyzed first, and the expression of DC boost voltage ratio and the time-domain expressions of various key variables are derived. The operating waveforms of the NS-TSI are obtained accordingly. Furthermore, the NS-TSI is compared with the TSI to verify that NS-TSI possesses better DC boost voltage ratio. The experimental results verify the correctness of the theoretical analysis.