Abstract: Thornthwaite's potential evapotranspiration (APE ) and moisture index (IM) of 112 dominants and main companions of subtropical evergreen broadleaved forest in China have been calculated.The five climatic type of dominants and main companions have been divided using therma1 and moistural climatic classification.The groups of Thornthwaite's water-temperature distribution of dominants and main companions have been classified into five types.They are G1 (Microthermal semihumid type ), G2 (Mesothermal mesohumid type), G3 (Mesothermal humid type), G4 (Megathermal semihumid type), G5 (Megathermal mesohumid type).According t0 the result by calcu1ating climatological data of subtropical evergreen broadleaved forest zone using Thornthwaite's indexes, the potential evapotranspiration (APE) and index of moisture (IM) show geographical zonlities.There are close correlation among the climatological parameters and geographical indexes: latitude (LAT), longitude (LONG) and altitude (ALT).Their regression correlations show that in subtropical evergreen broadleaved forest region, while increasing each one degree of latitude towards north, APEwould decrease 25.28 mm and IMwould decrease 3.09; while increasing each one degree of longitude towards east, APEwould decrease 5.00 mm and IMwould increase 4.36; while increasing each 100 m of altitude, APEwould decrease 18.96mm and IMw0u1d increase 4.55.