An optical module comprising an upper portion of the housing with a bottom and two sides, a lower portion of the housing with a bottom and two sides, an electric component and an electroconductive sheet is provided. The two sides of the upper portion may be inserted between the two sides of the lower portion to form a relatively closed cavity for accommodating the electric component. A first convex block provided on the sides of the upper portion may be inserted into a gap which is formed between a second convex block and a third convex block provided on the sides of the lower portion. Thus, the first convex block, the second convex block and the third convex block may clamp the electroconductive sheet, thereby dividing the gap at the junction of the upper portion and the lower portion into a plurality of tiny gaps.