The over-plating technology was introduced to fabricate micro hole arrays, for it is difficult to fabricate a micro hole array with the size less than 10 μm by traditional methods. A mathematical model was presented to simulate the over-plating process by Finite Element Method (FEM). Using the optimized parameters (bake 120 ℃/60 min, exposure 3 000 mJ/cm2, and development 2 min),the AZ EXP 125nXT-10A resist structure in a diameter of 50 μm and a height of 50 μm was prepared, and then the over-plating technology was employed to shrink the micro hole. The experimental result shows that the simulation result is correct. Finally,a micro hole array in a diameter of 4 μm and a height of 70 μm was fabricated after over-plating 2 h. The result indicates that over-plating is a simple and low cost method to fabricate micro hole array, and it is suitable for batch production.