A fast nondestructive testing method using the normal terahertz time domain spectroscopy system (THz-TDSS) is presented and demonstrated in this paper. In the method a parallel THz wave with the beam size of 4 cm in diameter is used and an echelon is introduced in front of an object. The THz wave, passing through the echelon, is therefore delayed differently in one dimension. Then the THz wave takes the information in different positions of the object, which is corresponding to different delay times. Theoretical analysis indicates that the detected THz signal is sum of the information in different object positions and the information could be obtained from the compacted THz signal by deconvolution signal processing. In the experiment, top and bottom position of foil strip make signal having depression in the front and back respectively after deconvolution processing, and a number of foil strips corresponde to number of depressions. The different positions of foil strip with 4 mm width are detected successfully, and the number of foil strips is also distinguished clearly. A pushpin in diameter of 11 mm is tested twice and located by calculation. The experiments verfy that the theoretical prediction is correct and the fast non-destructive testing method is feasible. Beside the time saving, the other advantage of this method is simplicity in experiment because no any changes on the THz-TDSS is required.