The three-level neutral point clamped （3L-NPC） converters with conventional virtual space vector pulse width modulation （VSVPWM） scheme have some inherent disadvantages. For example， its reference voltage frequently passes through small triangle regions and it has a high total harmonic distortion （THD） of ac voltage which cannot be tuned by the amplitude of the virtual space vector. Aiming to solve the above issues， a modulation ratio tracking-based VSVPWM is proposed in this paper to reduce THD. First， the disadvantages of the division method of small triangle regions in the convention VSVPWM strategy are analyzed in detail. It is found that the THD of the line voltage in the 3L-NPC converter is very high when the conventional VSVPWM strategy is adopted. Second， the proposed VSVPWM strategy based on modulation ratio tracking is proposed in detail. It can be concluded that in the 3L-NPC converter with the proposed VSVPWM strategy when the modulation ratio is equal to the ratio of the virtual medium vector amplitude to medium vector amplitude， the minimum harmonic of the line voltage is achieved. At last， a 3L-NPC converter model in Matlab/Simulink is built to verify the proposed VSVPWM strategy， and the simulation results demonstrate that the proposed VSVPWM strategy is very simple， correct， and effective.