In order to improve the performance of Z-source inverters to meet different application requirements, by using small-signal model, an analysis has been made of the influence of capacitance and inductance parameters of Quasi-Z source inverters on the dynamic response of the system, followed by a research on the space voltage vector modulation (SVPWM) strategy, which divides the shoot-through vector into four segments (SVPWM4) and six segments (SVPWM6), as well as a comparison and analysis of the effects of two vector modulation methods on the maximum through duty cycle, maximum boost coefficient and maximum voltage gain performance of Quasi-Z. Compared with SVPWM6, the shoot-through zero vector of SVPWM4 is characterized with such advantages as the maximum value, a relatively small switching voltage stress, a low maximum inductance current ripple, and a better performance index. Finally, the correctness of the theoretical analysis can be verified by simulation.