Large magnetoresistance (MR) effect of non-magnetic p-n junction is an important issue in modern semiconductor electronic devices both experimentally and theoretically.Here we report a pronounced MR effect in silicon based p-n junction device at room temperature, and systematically measure the angular dependence of such MR effect with various magnetic field amplitudes and driven current.The experimental results show that the angular dependence of MR effect in p-n junction is proportion to sin2(θ), where the θ is the angle between the magnetic field and driven current.With the increasing the magnetic field and driven current the MR ratios are obviously improved.These results furnish an interpretation of the MR effect in non-magnetic p-n junction in terms of the Lorenz force induced by the magnetic filed.