For the soil and ore samples with complex composition and high sulfur content, the determination results of sulfur will be lower in the case of open acid dissolution due to incomplete sample digestion. 3.0g of sodium hydroxide was used as flux. 0.50000g of sample could be completely fused after melting in muffle furnace at 750℃ for 8min. After leaching with boiling water, the alkali metal and divalent metal ions were masked by adding tartaric acid. The solution was acidified with hydrochloric acid and then diluted. The content of sulfur in geological sample was finally determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). The linear correlation coefficient of the calibration curve was higher than 0.999. The limit of detection was 35μg/g. The experimental method was applied for the determination of sulfur in certified reference materials of soil, stream sediment and rock. The relative standard deviations (RSD, n=12) of determination results were between 1.6% and 5.0%. The found results of sulfur were basically consistent with the certified values, and the relative errors were not more than 4.6%. The actual samples of soil and rock with high content of sulfur were determined according to the experimental method. The RSDs (n=12) of determination results were not more than 1.6%. The proposed method could effectively solve problem for the determination of sulfur in refractory samples with high content sulfur. After treatment by alkali fusion and acidification, the sample solution could be used for the determination of fluorine by fluoride ion selective electrode method after adjusting the pH.