Pile foundation can effectively reduce the settlement of buildings and improve the safety of buildings,so pile foundation plays an important role in various buildings.Due to construction reasons,it may lead to pile defects,and the detection of pile defects is an indispensable part.According to the traditional hydrostatic load test,the displacement meter will change due to the damaged pile,which makes it difficult to accurately determine the location and shape of the defect.Other methods of detecting defects of the pile are expensive and cannot accurately determine the shape of the defect.Therefore,we propose VIC-3D digital speckle technique,a new defect detection method,to detect the position and shape of the defect.The digital speckle correlation method is a combination of modern speckle optics and digital image to measure the 3D deformation of the whole field of a defective pile.By analyzing the strain nephogram,the position and shape of the defect can be accurately determined.