Abstract: Layer by layer phase analysis of aluminide coating of a Ni - base supe-ralloy GH220 is carried out by physicochemical phase aaalysis and other physical instruments. The used samples of this alloy is aged at different time. Contents of β- NiAl and γ’ phases within various depth from coating surface was determined through simultaneous equations. The reasonable calculation of removed coating thickness is mado by correcting density. Trend of phase transformation in alurninids coating is presented. All calculations in this paper are programmed. Application of microcomputer in phase analysis is initially tried.