High performance hollow sphere(HS) boards were prepared using hollow sphere as raw materials. The influence of moisture content on the thermal conductivity of HS boards, expanded polystyrene(EPS) boards and glass wool(GW) boards was investigated. Besides, the effect of saturated water absorption and bulk density on the thermal conductivity of HS boards were systematically studied. The results show that thermal conductivity of samples increases with the increase of moisture content. When moisture content(by mass) is 5%, the growth rate of thermal conductivity of EPS boards, HS boards and GW boards is 604%, 667% and 846%, respectively. For the HS boards, when moisture content is less than 5%, the thermal conductivity increases rapidly; while moisture content is more than 5%, the thermal conductivity increases slowly. Growth rate of thermal conductivity of HS boards increases with the increase of relative saturation, thermal conductivity increases the more significantly especially for the higher water absorption samples.