A selective assembling type computing device includes a host computer and at least one peripheral device. The host computer has a first host external connection surface and a second host external connection surface, and the peripheral device has a first peripheral device external connected surface and a second peripheral device external connected surface. The peripheral device is provided for selectively assembling to the first host external connection surface or the second host external connection surface through assembling the second peripheral device external connected surface to the first host external connection surface or through assembling the first peripheral device external connected surface to the second host external connection surface. When the peripheral device is assembled to the host computer, the host computer detects the peripheral device to obtain at least one electrical operating parameter of the peripheral device to accordingly transmit a working power to the peripheral device.