This paper aims to reduce the thermal errors of the machinę tools by indirect compensation methods. Thermal effects can form more than 70% to the overall displacement error by using HSC technology. To compensate thermal expansion of the machine tool structure, exact measurement of machine thermal behaviour, as a function of temperature, is necessary. The temperatures, measured by the Pt 100 thermistor, are saved in the PLC of machine tool. Thermo-elastic deformations are calculated from the representative temperature-measuring points in the machine tool structure. The number of measuring points is optimized. We can directly determine the amount of expansion by multiplying the temperature value by a certain factor. The calculated defiections are compensated by means of the CNC of machine tool. We apply and test different methods to solution of deflection in the end point of the tool. My aim was to reduce thermal deflection by 3/4 and this aim has been reached.