A bow shock is formed in the interaction of a high-speed laser-driven plasma cloud with a cylinder obstacle.Its temporal and spatial structures are observed by shadowgraphy and interferometry.The width of the shock transition region is ～ 50 μm,comparable to the ion-ion collision mean free path,which indicates that collision is dominated in the shock probably.The Mach-number of the ablating plasma cloud is ～ 15 at first,and decreases with time resulting in a changing shock structure.A two-dimension hydrodynamics code,USim,is used to simulate the interaction process.The simulated shocks can well reproduce the observed.