Abstract: The magnet support structure is an important component of the International Thermonuclear Experimental Reactor (ITER). It is the key to carrying out mechanical characteristic analysis of the magnet support structure to ensure the normal operation for the whole reactor. Through the digital analyzing of strength and stiffness for the magnet support structure under all kinds of conditions, this paper gives the stress distribution and deformation of all parts for such structure under its conditions. The analysis results show all parts' maximum stress value for the magnet support structure is below allowable stress and satisfy strength requirement. The deformation for all parts is reasonable, and displacement and instability phenomena do not happen. By digital analysis, it can provide the theory design data and enhance the safety and reliability of the magnet support structure for the International Thermonuclear Experimental Reactor.