Abstract: ICP-AES was applied to the determination of silicon in cast aluminum alloys.Influential factors of the digestion process,including the amount of HF and H3BO3 saturated solution used,heating time,and saturated time were studied by orthogonal testing.Amount of sample taken was 0.050 0 g,and wavelength of 251.612(133) nm was selected as analytical lines for the determination.Under the optimum conditions,the proposed method was used in the analysis of two cast aluminum alloy (ZL 108,ZL 111A),the results obtained were in consistency with the known values.