Using the Monte Carlo method, we have investigated the effect of the external noise on the phase-separation dynamics in binary mixtures. It is found that the addition of the fluctuation has speeded up the pattern growth, and driven the system to form［1,1］oriented tilted strip formation. When the noise intensity is fixed and the noise acting probability is less thanp=0.015, the noise will erase the effect of the deep quench, and the system will avoid being frozen.With the increase of the noise acting probability, the structure factor will grow linearly. If the noise intensity is adequate, in an appropriate noise acting probability region, the system can form a high-oriented tilted strip pattern.