Abstract: Studied here in the essay are the physiochemical characteristics of the anti-corrosion pipe with Cr content ranging from 3% to 9%, and the effects by the contents of the alloy elements on the austenitizing temperature, phase transformation temperatures of cooling process and the micro-structures at room temperature. Results show that mixed structures of bainite/martensite are obtained, when the Cr content is no more than 5%, and the proportion of the two components depends on the cooling speed;the subtotal structures of the pipe with the Cr content more than 7% could transform to martensite at normal cooling speed. Furthermore the relations between the post-tempering micro hardness and the original structures of the pipe are also studied. The results indicate that the steel pipe with more volume fraction of martensite shows larger variation of the post-tempering micro hardness, which could be used to determine the heat treatment process, and control the mechanical properties of the anti-corrosion linepipe as well as the casings.