The growth， leaf morphology， chlorophyll synthesis and photosynthetic parameters in diploid and triploid Passiflora edulis Mantianxing were measured. The results showed that： （1） Compared with triploid plants， the triploid plants showed shorter stalk and petiole， narrower leaves and shorter distance between than that of diploid leaves， and the content of carotenoid was no significant difference. （2） The total content of chlorophyll， chlorophyll a and chlorophyll b synthesized by triploid leaves was higher in triploid. （3） During the diurnal process of photosynthesis， both diploid and triploid had a lunch break and the net photosynthetic rate （Pn）， transpiration rate （Tr）， stomatal conductance （Gs） and intercellular CO₂ concentration （Ci） of triploid plant were higher than those of diploid plant， which were increased by 9.5%， 6.9%， 4.5% and 3.9%， respectively. （4） The variation trend of monthly photosynthesis in diploid and triploid was similar， both reaching the highest value in August and falling to the lowest value in December， both of which are single-peak curves. The Pn， Tr and Gs of triploid Mantianxing are superior to diploid. （5） There was correlation between the indexes of the two ploidy plants， which indicated that the traits influenced and promoted each other to make the plant grow normally. The size， opening and closing of stomata significantly affected the Pn and Tr of plant leaves. These results showed that the photosynthetic capacity and light energy utilization capacity of triploid Mantianxing were enhanced with the increase of gene dose， and the accumulation of chlorophyll synthesis content of triploid Mantianxing was increased.