The aim of this research is to determine the thermal conductivity of apple tree leaves and the factors influencing the thermal conductivity. In this paper the natural material remain (leaves) usage as a thermal insulation material is discussed. In this study samples for a 2 factor experimental plan are created. The moisture content, density and the heat flow measurements for the calculation of the thermal conductivity coefficient are carried out for the samples. The main factors that influence the thermal conductivity are density and particle size. This paper will evaluate the possibility of a natural material rational usage in making thermal insulation.