Abstract: Microstructure and mechanical properties of a new developed CO2 corrosion resistant Cr containing (1wt%-5wt%)pipeline steel were investigated by optical microscope,scanning electron microscope,tensile tester and impact tester.The effect of the Cr content on microstructure and properties was studied.The results show that adding Cr element changed the microstructure of the steel from ferrite-pearlite to bainite with increasing the Cr content.The hardness,strength and ductile-brittle transition temperature increased with increasing the Cr content,while the ductility and toughness decreased.The impact toughness of the steels containing 1% and 3% Cr was superior to that of the X65 steel in a wide temperature range (above -120 ℃).