Abstract: In case of determining of trace hydrogen content in the steel with the O-N-H analyzer,the method of specimen-preparation directly affects the accuracy of hydrogen analysis result. In this paper,the effect by the specimen preparation method on the hydrogen analysis result is analyzed,involving the three aspects i.e.,the processing cooling method,the processing roughness and the cleaning effectiveness of the hydrogen specimen. It is revealed via the analysis that given that the processing temperature for the specimen is guaranteed,the measured H content of the specimen as water-cooled is the highest;the H content of the specimen with rough surface as measured is 3~5 times higher than that of the specimen with bright, smooth surface; and the ultrasonic cleaning method for the rough-surface specimen obviously affects the H content as measured,but produces no effect on the measured result of the specimen with bright and smooth surface.