The asymmetric deformation and eccentricity problems of near hemispherical diaphragm under the uniform surface load are quantitatively characterized in the paper.The analysis is based on a 3D finite element analysis (FEA) model established according to elastic-plasticity and large displacement nonlinear finite element method.Besides,the deformation experiments are taken to validate the reliability of FEA model which shows that the simulation results are in good agreement with the experimental results.Then,three angle parameters,deflection angle β,circumvolving angle θ and distributing angle γ,are introduced and expressed to characterize the asymmetric deformation and eccentricity quantitatively.According to the angle parameters,the inversion processes of uniform thickness diaphragm and varying thickness diaphragm are calculated respectively.The inversion process of varying thickness diaphragm is much steadier than that of uniform thickness diaphragm.The present results show that the asymmetric deformation process can be characterized by curve of three angle parameters (β,θ,γ) exactly,the degrees of eccentricity can be indicated by the final value of deflection angle and the eccentricity position can be characterized by the final values of the three angle parameters. The asymmetric deformation and eccentricity problems of near hemispherical diaphragms under the uniform surface load are quantitatively characterized in the paper. The analysis is based on a 3D finite element analysis (FEA) model established according to elastic-plasticity and large displacement nonlinear finite element method. In addition, the deformation experiments are taken to validate the reliability of FEA model which shows that the simulation results are in good agreement with the experimental results. Chen, three angle parameters, deflection angle β, circumvolving angle θ and distributing angle γ are introduced and expressed to characterize the asymmetric deformation and eccentricity quantitatively. A ccording to the angle parameters, the inversion processes of uniform thickness diaphragm and varying thickness diaphragm are calculated respectively. the inversion process of varying thickness diaphragm is much steadier than that of uniform thickness diaphragm.The present results show that the asymmetric deformation process can be characterized by curve of three angle parameters (β, θ, γ) exactly, the degrees of eccentricity can be indicated by the final value of deflection angle and the eccentricity position can be characterized by the final values ​​of the three angle parameters.