The Z-source NPC three-level inverter can realize buck-boost energy conversion without introducing extra dc-dc stage compared with the conventional three-level inverters. However, the problem of low-frequency neutral-point (NP) voltage oscillations is a drawback for its applications. In this paper, a hybrid modulation strategy based on the combination of double signals pulse-width modulation (DSPWM) and SPWM with injected zero-sequence signal is proposed, which can eliminate the low-frequency NP voltage oscillations under different conditions. First, based on the operating principle that average NP current should be zero in a switching period, the optimal solution of the compensation zero-sequence signal is calculated using the mathematic model of averaged NP current. And then, amplitude limitation of zero-sequence signal is set to avoid affecting voltage boosting. The DSPWM is adopted if the value of zero-sequence signal is bigger than the amplitude limitation, otherwise, zero-sequence signal injection method is selected. The proposed hybrid modulation strategy can realize NP voltage oscillations elimination and voltage boosting simultaneously. Finally, the performance of the hybrid modulation strategy are verified by simulation results.