Through this study, thermal conductivity of polymer hybrid composites filled with natural particles will be studied experimentally. In this study, A modified hot wire method is used to measure the thermal conductivity of the composites consisting of polyester matrix filled with neutral particles of date and olive up to 15% by weight ratio. With the increase in the density of natural materials, date kernel powder and olive powder additives to polyester to form the compounds filled with it, there is an irregular increase in the thermal conductivity. With increasing the temperature, thermal conductivity decreases to give good insulated composite material.