The present invention is an electrical signal computing module capable of accommodating printed circuit board, able to lead the exterior air into the main case body, exchange heat with the printed circuit boards, without accumulation of heat and damage of the printed circuit board. The present invention has a main case body with a bottom case and an internal board set, and four accommodating areas are formed by the internal board set and a transmission circuit board, in addition, numerous flow holes disposed at specific position are designed for air flowing in, exchanging heat produced by printed circuit boards as well.