Abstract:The incomplete diffusion of Sn during the phase formation process of Nb3Sn superconductors significantly affects their superconducting properties, thus limiting their application fields. Laser induced breakdown spectroscopy（LIBS）, as a fast and non-destructive detection technique, has advantages such as non-destructive sample testing and rapid response. This article uses LIBS technique to study the effect of doping 0-7at% Ta on the Sn diffusion behavior during the preparation of Nb3Sn by Sn diffusion method. And visually observe the effect of Ta doping on Sn diffusion behavior. The influence mechanism of Ta doping on the preparation of Nb3Sn samples by Sn diffusion method was investigated through the observation of microstructure and superconductivity. A certain amount of Ta doping is beneficial for reducing the grain size in the sample, thus providing more grain boundaries. Grain boundaries are the main channels for Sn diffusion, promoting the diffusion of Sn in the sample and facilitating the synthesis reaction of Nb3Sn. The synthesis of Nb3Sn further promotes the diffusion of Sn. Therefore, the smallest grain size and uniform distribution were obtained when doping the 5% Ta sample, and according to LIBS data, the maximum diffusion depth value of Sn was obtained. Therefore, the 5% Ta sample has the best superconductivity. From the above results, it can be seen that a certain amount of Ta doping effectively solves the problem of incomplete diffusion of Sn element in the preparation of Nb3Sn samples. On the other hand, it confirms that LIBS technology can provide intuitive and effective criteria for Sn diffusion behavior, supporting the potential application of LIBS technology.