Despite the fact that spring energized C-rings are widely used in nuclear power plants for flange seal, few studies are carried out to highlight the complex mechanical behaviors of the C-ring. A three dimensional nonlinear finite element analysis is developed to examine the compression recovery performance of the spring energized C-ring. Through the analysis, it is found that the compression recovery curve of the spring energized C-ring can be simplified to three straight lines. Two dimensional parameters, including the inner lining thickness and spring wire diameter, are studied to determine their impacts on the spring energized C-ring. Relations between the compression recovery curve and spring wire diameter are concluded and expressed by specific equations. Moreover, the deformation and contact stress distribution of the C-ring are also studied. The validation of the finite element model is confirmed by the experimental method.