The effect of horizontal magnetic field on magnetoresistance was studied by TCAD simulation. At low concentration 10<sup>14</sup> and 10<sup>15</sup> cm<sup>-3</sup>, the magnetoresistance linearly depends on magnetic field density and direction. The percent of magnetoresistance (%MR) of this study is less than 1 % at biased current 1 mA, 0.5 T. The unbalance between Lorentz's force FL and Hall electrical force FH causes this effect. The positive and negative % MR of magnetic field in -y and y direction are caused by FL > FH. At the high concentration 10<sup>16</sup> - 10<sup>19</sup> cm<sup>-3</sup>, the Lorentz's force and Hall electrical force are nearly equal. The magnetoresistance is a little bit positive both in -y and y magnetic field direction which are caused by FL > FH and FH > FL, respsctively.
