Abstract: By modeling the relationship between transpiration rate and some factors respectively，the relationships between 1ear transpiration rate and the factors such as photosynthesis rate，stoma conductance，etc．are studied．The results show that there are close relationships between leaf transpiration rate，and leaf and air temperature，relative humidity，difference of vapor pressure，stoma conductance radiation and CO₂ density difference．Upon this environmental，micrometeorological factors，the leaf and air temperature，relative hum idity have high influence on the leaf transpiration rate，the total solar radiation has low influence，the wind is lower as it is weakly．