Abstract: With new 20 steel pipes in different states and fractured 20 steel pipe as study examples, the yield strength and tensile strength of the pipes were tested by the continuous ball indentation method and conventional tensile method respectively. The results show that the continuous ball indentation method could accurately reflect the changes in the mechanical properties of 20 steel pipes before and after strain aging and could be used to non-destructively test the mechanical properties of 20 steel pipes in different states.