Abstract: Analyzed are the elements as affecting the measurement uncertainty of contents of C and S in the linepipe-purposed steel by means of using the HF induction furnace combustion infrared absorption method as per Standard JJF 1059.1—2012. And relevant math model is set up，and the uncertainty of the result from measurement of C and S contents of the said steel is evaluated. Also done is determining and calculating each individual uncertainty component as identified during measuring process. Based on the result of comparison of the uncertainty components，it is revealed that the uncertainty of Standard B acts as the main source of uncertainty of C and S contents analysis，while the instrument indication error uncertainty makes the largest contribution to the total uncertainty.