Three-dimensional finite element models of standard ellipsoidal heads with large opening nozzle structure are built for calculation, and the stress distribution is analyzed. An analysis reinforcement method of standard ellipsoidal heads with large opening is proposed, which can be realized though equivalent stress coefficient computation. Experimental stress analysis on typical structure with large opening is conducted by resistance strain measurement. The experimental results show good agreement with finite element calculations, relative error being less than 10% which meets the requirements of engineering design. Then the accuracy of analysis reinforcement method of standard ellipsoidal heads with large opening given in this paper is verified.