A beam alignment system for extreme ultraviolet lithography light source system is designed to meet the requirement of beam pointing stability of extreme ultraviolet lithography light source system and ensure the conversion efficiency of extreme ultraviolet light. The alignment system is composed of two parts, the beam jitter detection module and the beam alignment module. By analyzing the beam jitter mechanism and beam control principle, a closed-loop alignment system with detection and control is built based on the virtual instrument development software LabVIEW. The experimental results show that after the beam passes through the alignment system, the jitter amplitude in the horizontal direction is less than 2 μm, the jitter amplitude in the vertical direction is less than 4 μm, and the pointing stability is less than 6 μrad, which meets the requirements of the light source system for the beam pointing stability.