Abstract: wideThe application of spectro-chemical analysis to high alloy steel in our steel works has been limited by the accuracy of their methods. Through the investigation upon two typical high alloy steels, ‘P18' high speed steel and ‘Я1' stainless steel, it is proved that the minimum standard deviation that can Le reached by the photographic method of epectro-chemical analysis of such high alloy steels after adopting many improvements in each step of the analysis is about 1%. Many valuable experiences from our steel factories are introduced in this paper, and the problems concerning accuracy of the spectro-chemical analysis of high alloy steels are discussed.