The active twist control of helicopter rotor blades by an application of macro-fibre composite (MFC) actuators leads to significant vibration and noise reduction without the need for complex mechanisms in the rotating systems. For the reason of environmental improvement an optimal design methodology based on the planning of experiments and response surface technique has been developed for an active twist of helicopter rotor blades consisting of C-spar made of unidirectional GFRP, skin made of +450/-450 GFRP, foam core, MFC actuators embedded into the skin and balance weight. The structural static analysis with thermal load, static torsion analysis and modal analysis using 3D finite element models have been developed using ANSYS for the optimal design. In this case thermal strain analogy between piezoelectric strains and thermally induced strains is used to model piezoelectric effects. The optimisation results have been obtained for four design solutions connected with the application of active materials.