Abstract: Test study is conducted on the properties of the SEW-80TT high collapse-resistant casing that is developed with the SEW process(high-frequency welding + hot stretch-reducing),involving such properties as microstructure,residual stress,tensile strength,impact strength,external collapse-resistance and grooving corrosionresistance,etc. The test study result shows the property data of the said casing,i.e.,collapse-resistance:12.4% higher than the HC2 value as specified under Specification Q/SY 1394—2011,and 41.6% higher than what is required in Specification API TR 5C3—2008;residual stress:less than 100 MPa;yield strength:over 685 MPa,and impact values:base metal—above 126 J and welding seam—above 118 J. Accordingly,it is concluded that the SEW-80TT high collapse-resistant casing is in possession of satisfactory collapse-resistance and comprehensive mechanical properties as well.