The present invention provides a circuit board having an isolation cover and an assembling method thereof. The circuit board of the present invention comprises a main body and an isolation cover disposed on the circuit board main body. The main body and the isolation cover have a plurality of corresponding first and second positioning portions, and a ground portion is disposed on at least one side of each first positioning portion. The isolation cover is disposed on a first surface of the main body, and each second positioning portion passes through a second surface of the main body and each first positioning portion. An end of each second positioning portion is connected to each ground portion.