Abstract: This paper deals with the in-plane bending of orthogonal wound GRP circular-shaped curv ed tubes.The features of the tubes are orthotropic,varied in thickness and without coupling effect.A series of formulas are developed for calculating the stresses and deformations of the tubes under the in-plane bending by applying the energy nethod and the ring shell theory. The their limitations are specified.Formulas for estimating the maximum stresses are given herein and demanstrated experimentally.