Abstract: The authors used Huanghua pear as a test material and studied the effects of leaf age and different positions on canopies on rate of photosynthesis. It was shown by the results that the leaves of Huanghua pear exported a few photosynthetic substances on 11th day after spreading leaves, the net rate of photosynthesis of single leaf approximated to maximum on 25th day, and the thickness of high photosynthetic leaf canopy was about 125 cm in dense planting pear trees.