Total sulfur content is a mandatory item in soil investigation projects.In the sulfur analyzer that directly determines solid samples using the combustion method，the high-frequency infrared carbon-sulfur analyzer has the advantages of low detection limit，fast detection speed，high combustion temperature，and high accuracy in determining soil standard substances，making it the best instrument for rapid determination of total sulfur in soil.In the process of sample determination using high-frequency infrared carbon-sulfur analyzer，the crucible blank，oxygen flow rate，sample weight，flux addition amount，and quantitative method would all affect the accuracy of the measurement results.By optimizing the above influencing conditions，the optimal conditions for analyzing the total sulfur content in soil were determined:in the case of strictly controlling the crucible blank，the oxygen blowing flow rate was set to 2-3 L/min，and 0.1 g of sample(accuracy:0.0001 g)，0.5 g of pure iron(accuracy:0.001 g)，and 1.0 g of tungsten particle flux(accuracy:0.001 g)were mixed and then analyzed on machine.Samples of different concentrations were calibrated in sections.It is worth noting that this study has confirmed the feasibility of establishing a working curve using chemical substance standards，providing valuable ideas for instrument optimization and improvement in the later stage.The relative standard deviations(RSDs)of the measured results of national soil standard substances were less than 2%(n=6)，the absolute value of the relative errors(REs)between the measured values and the standard values were less than 1%(n=6)，and the detection limit of the method was 4.50 μ g/g，indicating that the method had high accuracy and precision，and was suitable for batch testing of soil samples with low sulfur concentrations.