Abstract: The optimized designing methods is obstained by ANSYS. Its object is the fans fixed on the computer box surface. The cooling performance of the fans was test through experiment with an empty computer box, At the same time, the simulation by ANSYS was performed under the same conditions. Based on the preceding results, the feasibility and accuracy by software simulation is proved. Then the software phantom imitating a real integral computer box cooling system performance was set up, and according to the simulation outcome, the suggestion of the optimized fans position was given out. Thus the utility of sofeware simulation was verified.