Abstract: Three-dimensional Navier-Stokes equation was numerically solved to investigate the flow structure and characteristics of spiked body flying at M_\infty =6.0 with 10^\circ angle of attack. With reasons for the deterioration of aerodynamic force pointed out, bayonet shaped plates were set to improve the flow field and aerodynamic characteristics. By comparing the actions of plates with two different configurations, the mechanisms for the bayonet structure can be stated as formation of circumfluence and shear layer at windward side due to the plates splitting the flow field and depressing flow in toroidal direction, which will drive conical shock to move away from axial line, lower the strength of interaction between flow structures around the blunt body and weaken the perturbation at leeward side.