Abstract: In order to investigate the effects of biochar application and irrigation amount on soil physical properties and crop growth physiological characteristics, a field comparative experiment was carried out. Taking greenhouse tomato as the experimental object, three biochar application treatments: B0（0 kg/m~2）, B1（2.5 kg/m~2）, B2（5.0 kg/m~2） at three irrigation water level: T1（1.4Ep）, T2（1.2Ep）, T3（1.0Ep） were set, where Ep was the cumulative water surface evaporation. The response of soil physical properties, tomato growth, photosynthesis and other physiological indicators to the application of biochar with different irrigation amount was observed and analyzed. The results show that the proper addition of biochar could effectively increase the soil. The maximum volume moisture content of soil water retention is 21.9% and 32.1% compared with B0. Treatment B1 is beneficial to the long-term water holding capacity of soil. The soil bulk density is reduced by 2.5%-16.6%, and the soil porosity is increased by 1.9%-10.5%. The application of biochar application（B1） could effectively improve the stomatal conductance and photosynthetic rate of tomato under full irrigation and moderate de-ficit treatment. Treatment B1 and B2 increase the photosynthetic rate by 11.4% and 54.8%, respectively. It is observed that under T3 condition, the photosynthetic rate under B1 and B2 shows less than the photosynthetic rate under B0 by 16.7% and 50.6%, respectively.