Sulfur is one of the harmful elements in coal, the sulfur dioxide produced during its combustion not only seriously pollutes the air, destroys the ecological balance, but also corrodes the boiler pipeline, so it is extremely important to quickly and accurately detect the total sulfur content in the coal. Coulomb titration method is widely used for testing total sulfur content in coal in many mining enterprises and testing institutions due to the advantages of simple operation and high level of automation. The influence of the dosage of WO3, the airtightness system, the tirring speed and the air flow rate on the accuracy and precision of the determination of sulfur content by coulometric titration method was studied, and the measures to improve the accuracy and precision of the measurement were discussed.