Controlling current in critical conduction mode (CRM) to achieve zero voltage switching (ZVS) of switches is an effective way to improve the efficiency and power density of inverters without additional hardware costs. However, the switching frequency of CRM-based inverters is varied widely, which brings difficulties in designing the LC filter. In this paper, an optimal LC filter parameter design method based on power loss analysis is proposed to achieve both high efficiency and low inductor volume. A single-phase neutral-point-clamped (NPC) inverter with 400 V dc-link voltage and 1 kW rated power is taken as an example to indicate the proposed design method. Experimental results show that the inductor core volume can be decreased by 33%, and the peak efficiency is 98.3%.