In this paper,we have theoretically studied the field distributions and resonance absorption in a laser plasma filament. Under the condition of cold plasma, the field equation, as well as its analytical solutions to the radial and axial components of the electric field, is derived. By the numerical calculations, it is then found that at tunnel effect exists along the radial direction in a filamentation plasma, i.e., the field reaches a maximum near the radial resonance absorption point r0.