With the advantages of higher resolution, higher accuracy, in-situ image of borehole wall even in muddy slurry and sufficient post-processing softwares, the borehole acoustic televiewer can supply abundant useful information for foundation analysis in civil engineering investigation. This technique has been widely used abroad but has seldom been utilized in China. This paper gives a brief description of the principle of the borehole acoustic televiewer survey as well as the related technique and deals with the data interpretation.