Abstract: The ding/dent may be generated in heat transfer tubes of PWR stream generator during the manufacturing and installation process, the dimension of ding/dent including its depth, length and width should be provided if residual stress analysis, wall thickness loss calculation and operational life assessment are carried out. This paper described a method for measuring the depth of ding/dent using video endoscopy, measuring the length of ding/dent using internal bobbin eddy current technique, and measuring the width of ding/dent using internal phase array eddy current technique, in response to the tubes were already installed and cannot be directly measured due to the geometric configuration limitations of the steam generator. This dimension measurement technique provided a basis for quantitative analysis of the tube ding/dent and accumulates valuable experience for the similar quality problem of heat exchanger of nuclear power plant.