Abstract: Shots and receivers are placed on the ground surface around the studied area ; the observation is performed by using conventional seismic method. The energy exited from sources arrives at receivers. The signals recorded are processed by tomographic inversion and a P-wawe velocity image is produced. The image shows velocity distributions in shallow layers and weathering deposits, as well as geological structure of bedrock. This technique was used in an engineering-geological survey. The velocity CT image obtained is coincident with geologic outcrops and excavation result.