Abstract: The profitability is different in the modification of standard rootstock and big canopy with different tree shapes in current pear cultivation. The aim is to select and determine the suitable tree shapes by measuring the amount of shoots，canopy transmittance，photosynthetic characteristics，leaf nutrients，fruit yield and qualities in the process of modification. This study was carried out in four tree shapes for two consecutive years. The results showed that the photosynthetic active radiation，the net photosynthetic rate，transmittance，the leaf fresh weight as well as the leaf nutrient contents of N，P，K were significantly different in the four tree shapes with the same total shoots，the number of spur shoot and the ratio of spur shoot and total shoot. The yield and fruit qualities were also different in the four tree shapes. The conclusion was obtained that the single open centre shape in pear should be selected in the modification of pear with standard rootstock and big canopy，while the tall-spindle was better inother canopies when the top-grafting forvariety improving was carried out.

Key words: pear, tree shape, transmittance, yield, fruit quality