Abstract: The axial-flow check valve is a key element in prevention of back flow. During its design, theoretical equations are adopted to calibrate strength and analyze sealing conditions of valves. However, the method may not establish effective mechanical model for elements with complex internal structures. Using finite-element analysis software, the finite-element technique may be used to construct 3D models to simulate and analyze constraint and loading. The stress, deformation and specific pressure of sealing surface under experimental and application pressures of complex elements in these valves are outputted. According to the rules of ASME for construction of pressure vessels, rationality of design of key elements and reliability of sealing structures in valves are assessed. In this way, the technique can be used to display stresses, deformation and distribution of sealing specific pressures of elements accurately, directly and quantitatively.