Abstract: The coilayer vessel is considered as an integral composed of inner cylinder, layer cylinder and outer cylinder. The layer cylinder is taken as an integral cylinder of orthotropic material, and the additional strains induced from the clearance and slippage between winding layers are accounted for in the variation of elastic coefficients of the layer cylinder material. A differential equation for determining the radial stresses of layer cylinder is obtained through a series of theoretical analyses and derivations. A coilayer vessel of inside diameter 605 mm was numerically analyzed. Electrical measurements of stresses and bursting tests were also undertaken. The calculated results well checked with the experiments, the error is less than 2.7% and the results are more accurate than those obtained from the conventional thick cylinder calculation methods.