High frequency sinusoidal inverter is used more and more. It is much helpful to do quantitative analysis of its modulated model for systematic parameter design and project optimization. The modulated models of three major pulse width modulation（PWM） methods for sinusoidal inverters are deduced from means of dual Fourier transform. A new unipolar sinusoidal PWM（SPWM） method is proposed and the corresponding modulated model is also established. Through the analysis and comparison of various modulated methods， the optimal modulated strategies under different occasions are determined， such as: for the single-phase full-bridge inverter， double-frequency SPWM and unipolar SPWM are the optimal choice; for the combinative three-phase inverter， new unipolar SPWM is the optimal one. Theoretical analysis is verified by simulation and experiment.