A direct numerical simulation (DNS) of two dimensional, conducting turbulent channel flow under the action of applied streamwise magnetic fields was performed based on the low magnetic Reynolds number approximation. The numerical results with Re=10 000 under the action of different magnetic interaction numbers ranging from 0.001 to 10 were analyzed. The computed variations of the near-wall velocity distribution, root mean squares (RMS) of the fluctuation velocity, and the Reynolds stresses were presented and compared to the case with neutral fluid. The results show that streamwise magnetic field results in an upward shift of the log layer, the maximum of Reynolds stress varies linearly with interaction number. With the increment of interaction number, the time evolution of average vorticity of the bottom wall shows a growing trend in periodicity and the average vorticity of the bottom wall becomes a constant value finally when relaminarization happens.