This paper discusses the stiffness characteristic of a 2(3HUS+S) parallel manipulator. This manipulator can be applied to hip joint motion and simulate two hip joints in the same time. The stiffness of the manipulator components is given by Hooke's law, and the global stiffness matrix model is established based on the virtual work principle and the Principle of deformation superposition. The local and global stiffness characteristic evaluation indexes are defined. In the workspace of the manipulator, a numerical simulation of stiffness is conducted using MATLAB. The stiffness characteristic of this manipulator is assessed by analyzing the influence of the attitude parameters and structural parameters on the stiffness indexes. Finally, the structural deformation of the virtual prototype of the manipulator is analyzed under several typical attitudes using ANSYS Workbench. The experiment results from the virtual prototype are compared with those from the numerical simulation, and the analysis result verifies the Validity and correctness of the stiffness model and indexes of the 2(3HUS+S) parallel manipulator.