For the technical problems in eddy current testing of stainless steel thin-walled flat tube,the equivalent filling coefficient calculation method of eddy current testing coil was adopted by analyzing the characteristics of flat pipe forming process.According to the sensitivity difference of the profile,a reasonable testing process was developed, and the eddy current testing of the stainless steel thin-walled flat pipe was effectively realized.Destructive tests and flight tests verify the reliability of the inspection process.The eddy current testing technology has been applied to several types of thin-walled flat tubes.