In this investigation, a new thermal insulation material (RSTIB) from rice straws with a low density of 200–350 kg/m3, a thickness of 40 mm and the thermal conductivity of 0.051–0.053 W/(m K) was developed using high frequency hot-pressing. It could be used asa component of construction material as wall or ceiling insula-tion for energy conservation. Thermal conductivity was found tobe correlated with the boards’ density and ambient temperature. Additionally, the thermal conductivity increased with decreasing particle size, and the results showed that the particle MC