Abstract: Cell shape was modeled as a rectangular casket with a thin and long hollow from the cell structure of wood biologically. Theoretical expression of wood thermal conductivity in transverse direction was derived by the analogism, i.e. drawing an analogy between heat conduction of the material and its electric conduction. Then, the rules were revealed from this expression by applying mathematical analysis that: wood thermal conductivity in transverse direction was a decreasing function of wood porosity; for the wood having the same moisture content, the thermal conductivity increased with the increase of density; for the same wood, the thermal conductivity in creased because of higher moisture content. Finally, theoretical expression of wood thermal conductivity in transverse dirction and all conclusions drawn in this paper were verified by testing data of wood thermal conductivity in transverse direction of 27 tree species of wood.

Key words: wood, thermal conductivity, transverse direction, theoretical derivation, influencing factor, change rule