This paper proposes a more accurate eccentricity and tilt measurement method based on Young's interference experiment. The basic principle of the method is introduced first before the method is simulated. Then the results are obtained when a to-be-adjusted focusing lens with eccentricity and tilt is simulated. The optical sensitivity also is obtained from these simulation results, and the expression for the change in optical path length caused by eccentricity and tilt is analyzed. Use of this method to detect eccentricity and tilt and assist in adjustment of the system allows the instrument to achieve higher accuracy and thus obtain improved imaging quality and spectral resolution.