An electroelastic actuator on the piezoelectric or electrostriction effect is applied in nanotechnology, nanobiology, biomechanics and adaptive optics for the precision matching in nanomechatronics systems. For the analysis and calculation of nanomechatronics systems is used the harmonious linearization of the hysteresis characteristic for an electroelastic actuator. The piezo actuator works on the basis of the inverse piezoelectric effect due to its deformation when the electric field strength is applied. To increase the range of movement of the piezo actuator to tens of micrometers, the multilayer piezo actuator is applied. The piezo actuator is used in nanomechatronics systems for nanodisplacement in adaptive optics, nanotechnology, scanning microscopy, nanobiomechanics, multicomponent telescopes. The coefficients of harmonious linearization for the basic loop characteristic are determined by the method of the theory of nonlinear automatic systems. On the characteristic of the piezo actuator deformation from the electric field strength, the initial curve is observed, on which the vertices of the basic hysteresis loops lie. The basic hysteresis loops have a symmetric change in the electric field strength relative to zero, and partial loops have an asymmetric change in the strength relative to zero. The expressions for the hysteresis basic and local loops of piezo actuator are received. The coefficients of harmonious linearization for the basic loop characteristic of the piezo actuator for nanomechatronics systems are obtained. The basic and local loops for hysteresis characteristics of the piezo actuator are proposed. The expression is determined for the generalized frequency transfer function of the nonlinear link with the hysteresis characteristic of the basic hysteresis loop for the piezo actuator.KeywordsHarmonious linearizationHysteresisBasic and partial loopsDeformationElectroelastic actuatorPiezo actuatorNanomechatronics system