Abstract: Evaporation loss is an important indicator to characterize oil quality. The Noack B method for non-wood alloy in The current industry standard NB/SH/T0059-2010 "Standard test method for evaporation loss of lubricating oils by the Noack method" has the advantages of being non-toxic, able to simulate the actual working conditions of engines and accurate test results, and is widely used in the industry. This paper studied the influence of different factors including sample addition amount, heating temperature, heating time, and pressure difference of vacuum pump on the experimental results and the uncertainties introduced in the process of Noack B method measurement. The research results show that when the sample amount is changed at (65±0.1) g, the test result change is ±0.019%. The fluctuation of the heating temperature at 245.2℃±0.5℃ may cause the test result change not more than ±0.27%. The variation of heating time per 5 s may cause less than 0.02% of the test results. The variation of measurement results caused by the pressure fluctuation of vacuum pump pressure at (20 ± 0.2) mmH₂O is ±0.04%. The uncertainties introduced by the sample addition amount, heating temperature, heating time, and vacuum pump pressure difference are 0.011%, 0.16%, 0.01%, and 0.02%, respectively, and the expanded uncertainty introduced by each influencing factor is 0.32% (k=2).