Abstract: To investigate the sex differences of Broussonetia papyrifera (L.) Vent., the main anatomical characteristics of the female and male plant leaves were observed and compared using paraffin sectioning. (1) Leaf epidermis, mesophyll, and vein anatomical structures of the female and male plants were compared. Common features showed there was only one layer of cells on the upper and lower epidermis, with thick cuticles and rich trichomes, and the palisade tissue was highly developed in the mesophyll; furthermore, the vascular system proportion was very large; (2) There were some differences in cell size and thickness among various types of tissue. Upper epidermis thickness, palisade tissue thickness, xylem thickness, and main vein vascular bundle thickness in the leaves of male plants were significantly higher than those of female plants, and significant differences were observed among related indicators such as the palisade tissue to spongy tissue thickness ratio, tightness of leaf tissue structure, looseness of leaf tissue structure, and percentage of xylem area accounting for vascular bundle area. These results showed that the leaf anatomical structure of this species not only had typical xerophyte leaf characteristics, but also showed significant sex differences between the male and the female, which might be related to their reproductive allocation.