Abstract: A method for the determination of biogenic opal with a wide content range in marine sediments using inductively coupled plasma-atomic emission spectrometry (ICP-AES) with wet alkaline digestion was reported in this paper. The chemical pretreatment procedure and instrument operation parameters for biogenic opal analysis were optimized. The detection limits of the instrument and method for biogenic opal were 0.724 μmol/L and 0.942 μmol/L respectively. The method has been verified by analyzing the National Standard Reference Materials (NSRMs) of GBW 08648 and GBW 08649 and the analytical results of biogenic opal in these two NSRMs were in agreement with the certified values with precision of 0.443%RSD and 0.527%RSD respectively. The method has also been applied to the determination of biogenic opal in marine sediments with precision of less than 8.9% RSD and provides a simple, accurate and efficient means for biogenic opal measurement in climate and environment investigation with various temporal and spatial scales in paleoceanography.