Abstract: The changes of main water parameters(MWP),including φ8sat (maximum osmotic potential at water saturation point), φ8tlp (osmotic potential when a plasmolysis just emerges), Ftlp (relative content of osmotic water), RWCtlp(relative water content)and AWC(relative water content in apoplast),in Pinus tablaeformis with season and provenance were studied by means of pressure-volume curve The result showed that the MWP in P-V curve of P. tablaeformis changed in response to the changes of both the growth and development stages and the environmental conditions. Among these parameters,φ8sat , φ8tlp Ftlpand RWCtlp were the highest during the stage of a growth peak in summer,then reduced gradually, and reached down to the lowest in cold winter. These parameters increased again when spring comes. However, the change trend of AWC was the opposite. Changes in MWP of P. tablaeformis with season were rather consistent with tree’s cold hardening. The difference in MWP of P. tablaeformis from different porvenances was remarkable, especially in winter. The synthetical index calculated from MWP indicated that of the climatic ecotypes of P. tablaeformis drought resistance had following order from strong to weak:northeast,central, east,southwest, northwest, centralwest and south type.