This paper introduces a new test model and data acquisition plan for evaluation of materials of thin-walled tubes of nuclear power plant.In analogy to crack growth rate measurements using compact tension(CT)specimens,a test model using thin-walled tube specimens has been established,and the corresponding mechanical and electrical finite element analyses have been made,which determined the data acquisition plan based on Direct Current Potential Drop(DCPD)method.The Pin-Loading Tension Specimens [1-3] have been used as the tested specimens to get the axial crack growth rate.The validation fatigue test has been taken in air at room temperature and atmospheric pressure on nickel based alloy 690.The relative error of crack length obtained from measurement system and the actual one obtained from optical microscopy is 21.625%,which indicates the reliability and accuracy of the test method and system introduced in this paper.