For effecting of SOD on apoptotsis of arsenic compound induced, active oxygen is found to be involved in apoptotic progress affected by exogenous SOD and measurement of SOD in cell sap. Arsenic compounds cause a decrease of SOD in cell, promoting active oxygen to produce in mitochondria, ceil apoptosis and active oxygen to react with SOD. Quantititive SOD are ccpsume by arsenic compounds. It is exacdy the decrease that make plenty of active oxygen gather in mitccnondria, and starts the apoptotie progress. It is result that SOD protects, ceil in apoptosis. The analysis of SOD values shows that active oxygen has an effect on apoptosis.