Abstract: This paper offers a method to measure leaf’s fractal dimension(FD)by introducing the box-counting dimension, one method the fractal theory provided.The scanned photos of mature leaves are treated according to the box-counting dimension.We use this method to measure the leaf’s FD of Osmanthus fragrans Lour.By analyzing the result, we find that:(1)The goodness of linear fit of double-logarithmic plot of the number of boxes to box size is significantly great:all the absolute values of coefficient of correlation are grcatcr than 0.999 1 that is very close to 1,the expectation.So we conclude that leases have typical fractal characteristics,which can be studied by fractal theory.(2)The FDs of all leaves of Tree 0.1 from the sample are between 1.7258 and 1.8880,with an average of 1.8065,a standard deviation of 0.0393 and a coefficient of variation(CV)of 2.7180%,which imply the low discreteness.A,nd all the data are normally distrilauted as vsrell.Other trees in the sample share the same case,so we conclude that the mature leaves of the same tree have the same FD statistically.(3)The ANOVA using rite completely randnm model shows that the differences between the 10 sample trees are not significant:F=0.706Osmanthus fragrans Lour share the same FD statistically.Therefore we presume that the mature leaves(or other mndule)of the same species share the same FD statistically.Finally we prnpnse an idea a, founding plant fractal taxonnmy.