The two-dimensional finite difference time domain (FDTD) technique was applied for numerical modeling and analysis of some typical application problems of ground penetrating radar (GPR) commonly in engineering inspections, including high frequency GPR inspection for highways pavement thickness, debonding in airport runways, voids in concrete structures and underground utilities. The modeling results give us a general idea of the capacity of resolution, the limitation and promises of application of GPR survey. Some case histories and test results on physical models are also given to show the successful applications of GPR technique to engineering inspection for highways pavement, airport runways, concrete lining of tunnels in Hong Kong.