Abstract: The interaction between a body in space and its plasma environment is one of the basic problems in space plasma physics. Based on a set of the coupled equations that describe the non-steady and non-linear interactions between plasma and the electromagnetic field in the wake region of a moving body in space, using the method of numerical simulation, the evolutions of the density distributions of charged particles and collapses of electric field are obtained. Considering the property of axial symmetry of field quantity, the initial conditions of two dimensions with three field components and the method of limited differencial, FTCS （time forward-differencial and space central-differencial method）, have been used. The initial condition must satisfy the condition of transverse wave ▽·Ê（ȓ,τ=0）=0 and the basic parameters in numerical calculation are V₀ = 10⁶cm/s, T_e = 2780 K, n_e⁰ = 1 × 10⁵ cm^-3, R₀ = 100 cm, Ê₀ = 0.15. It is noticeable that we take into account the effect of time derivative on the density disturbance and field distribution, which is not considered in previous researches. The results of numerical calculations show that the density cavitons and potential solitons are formed due to the modulational instability. Comparing with the previous works^[5]-[7], the velocity of the collapse is faster relatively. By detecting the distribution of density catiton, the moving body can be traced out by means of the change of the density caviton, although the body may be a stealth vehicle which can not be detected by the radar.