Modes of operation of horizontal ground heat exchanger of heat pump in Krasnodar region of Russia are investigated in this work. Ground temperature decreases from 3,6 °С to -1,6 °С in the area of the heat exchanger during the heating period due to increase of the heat removal of the heat exchanger from 25 W/m to 95 W/m, in this connection the coefficient of performance respectively decreases from 2,49 to 1,98. According to the results of mathematical modeling the temperature of the ground in the case of minimum heat removal reaches a temperature of undisturbed ground, the temperature of the ground in the case of maximum heat removal is reduced by 1 °C compared to the temperature of undisturbed ground.