The invention discloses a method for improving accuracy of a sulfur content measurement result. The method comprises A: putting a crude oil product into a combustion device, B: feeding nitrogen into the combustion device, a cooling device, a heating device and an absorption device, C: feeding oxygen into the combustion device and starting the combustion device, D: cooling the gas after combustion in the step C until the SO2 is cooled to form a liquid, E: heating the SO2 liquefied by the cooling device so that the SO2 is gasified, F: feeding the SO2 gas into the absorption device, and G: adding a hydrochloric acid standard solution into the absorption device drop by drop. The SO2 gas is liquefied by cooling so that the SO2 is separated from other gas, and the whole system is filled with nitrogen so that air is discharged by nitrogen and thus it is solved that the gas generated after combustion may contain other gas which can react with the aqueous solution of sodium carbonate and accuracy of a petroleum product sulfur content measurement result is poor because of undischarged air.