Abstract: As an advanced mechanical nondestructive testing method, nanoindentation technology can characterize the micromechanical behavior of materials. Parameters such as micro-elastic modulus and hardness can be obtained from the load displacement curve, but the mechanical constitutive relationship of materials cannot be obtained directly. In this paper, by adding Ni₃Sn₄ particles into Sn58Bi solder paste, the nonlinear stress-strain constitutive equations of four kinds of composite with Ni₃Sn₄(0, 0.3%, 0.5% and 1.0%) composites were obtained by means of the nanoindentation test and finite element simulation. The results of the nanoindentation test show that the elastic modulus and hardness decrease first and then increase with the increase of Ni₃Sn₄ content. The results of inversion analysis show that the yield strength obtained by adding Ni₃Sn₄ particles is higher than that without adding Ni₃Sn₄ particles.