A method for assembling an opto-electronic circuit board is described as follows. A bottom cladding layer, a core layer and a top cladding layer are formed on the base orderly such that a waveguide is completed. A first light-guide hole is formed in a base material, and a light source is disposed on the base material thereby forming an emission component. A second light-guide hole is formed in another base material, and then an optic receiver is disposed on another base material thereby forming a receiver component. A circuit substrate is processed in order to form a first cavity, a second cavity and a third cavity on a first circuit layer of the substrate. The waveguide, the emission component and the receiver component are disposed respectively in the first cavity, the second cavity and the third cavity.