In this paper, the techniques of modelling bolts in program ANSYS are investigated. Several types of the bolt models are proposed and compared. The finite element models with solid bolt with and without thread, and no-solid model. The pretension effect is applied for all types of bolts. Different types of connections and finite elements are used for modelling. In addition, the assembled mechanical structure is loaded by pretension effect and the field of stress and displacement of points around holes for bolts are investigated. Moreover, the stresses in the bolts computed by three-dimensional finite elements are investigated