Duck hepatitis A virus serotype 1 (DHAV-1) causes acute inflammatory injury with a very high mortality rate in ducklings, leading to severe economic losses worldwide, especially in mainland China. There is an urgent need to find new treatments to prevent and control infection with DHAV-1. Not only is there a shortage of commercial anti-DHAV-1 drugs, but there are also gaps in the use and protection rates of existing commercial vaccines. We previously found that icariin (ICA), an extract of Epimedium, can reduce the mortality rate of ducklings after DHAV-1 infection, and the effect of ICA after phosphorylation modification (pICA) is more evident. In this study, we used duck embryo hepatocytes (DEHs) to investigate the mechanism of the alleviation of DHAV-1-induced inflammation and oxidative stress by ICA and pICA, and to further study their effects on hepatocyte mitochondrial function, apoptosis and cell cycle. It was found that ICA and pICA can inhibit the negative effects of DHAV-1 on apoptosis and cell cycle progression by stabilizing mitochondrial function, thereby reducing inflammation and ultimately protecting liver cells. The effects of pICA are more beneficial than those of ICA. The results of this study may be useful in the development of a new prophylactic and therapeutic strategy against DHAV-1 and other acute inflammatory diseases.