In this paper, the application of double lens in Michelson interferometer experiment to measure laser wavelength and its influence on experimental results are discussed. By introducing a double lens system, we analyze the variation of spot size, ring pattern number and density, and discuss how to adjust the interference ring pattern by adjusting the lens distance. The experimental results show that the use of double lens system can significantly reduce the difficulty of Michelson interferometer adjustment, improve the experimental efficiency, and improve the accuracy of loop throughput counting.