Abstract: We semi-analytically addressed the evolution of poloidal disturbed magnetic field with plasma viscosity at different wave numbers.The influence of the wave number, plasma pressure and viscosity on the poloidal disturbed magnetic field was investigated by numerically solving the 2^nd-order ordinary differential equations of eigen-functions (ξ_r), derived from ideal magneto-hydrodynamics equations via Flourier transformation.The numerical calculation results show that depending on the plasma pressure, the wave number has a major impact.At a low plasma pressure, a large (a small) wave number results in a positive (a negative) poloidal disturbed magnetic field;however, at a high plasma pressure, a large wave number also corresponds to a negative disturbed magnetic field;and at a fixed plasma pressure, an increase of the plasma viscosity heightens the fluctuation amplitude of poloidal disturbed magnetic field.