With the improvement of computational capability, finite element simulation is an increasingly practical method to accurately predict the ultimate capacity and ductile fracture behavior of high-strength bolts. However, the mesh size affects the results of FE simulations but related research on mesh size effects is relatively limited. In the present contribution, the mesoscale critical equivalent plastic strain (MCEPS) is used as a failure index for calibrating the parameters of ductile fracture locus of high-strength bolts with different mesh sizes. The identified fracture locus is compared with a large bulk of experimental data taken from the previously published literature. The results showed that mesh size can have high effects on the calibrated parameters of the plastic constitutive relationship after necking and ductile fracture locus of high-strength bolts.