Abstract: Stress corrosion cracking of three kinds of oriented glass fibre reinforced plastics(GRP), including ±30°,±45°,±60°oriented GRP, were studied by fracture mechanics theory and compared with the stress corrosion cracking of unidirectional GRP. The results show that the fibre orientation affects on the stress corrosion cracking of GRP seriously. For the oriented GRP in this investigation, from better stress corrosion resistance to worse the order is ±30°,±45°,±60°oriented GRP. Compared with unidirectional GRP, oriented GRP demonstrate higher stress corrosion threshold loads, below which GRP can't fail in acceptable exposure time. Further discussions conform that fibre/matrix interface plays an important role in the stress corrosion cracking of oriented GRP and the crack growth mechanisms of oriented GRP and unidirectional GRP are different under different applied loads.