An apparatus for positioning and assembling of a circuit board includes a vacuum adsorption mechanism, an adjusting mechanism, at least four cameras, and a controller. The vacuum adsorption mechanism has a vacuum adsorption platform on which several holes are formed. The vacuum adsorption platform is connected to several vacuum, generators to control the adsorption and positioning of the main board of the circuit board. The vacuum adsorption platform has a through hole. The adjusting mechanism is mounted corresponding to the through hole. The adjusting mechanism is designed to enable the adsorbed daughter board to be adjustable in three axial directions. Two cameras are located corresponding to the main board. The other two cameras are located corresponding to the daughter board for detecting the optical points of the main board and the measuring points of the daughter board. The controller is electrically connected to these cameras.