The successful development of harmonic oscmation inverter with zero switchfor parallel output opens a mew way to solve the problem on a serious damdge of switchfor the large- power transistor in the common- used inverters.This paper describes theorking principle and inverting characteristic of this new inverter,and the important con-tribution which the large-power transistors are connected in parallel to increase the outputpower,including some meaesures to be taken for this parpose,This study will be of farreaching importance to some mine electric equipment and other electric equipment withhigh frequency,portability,high officiency and low cost.