The paper has established the models of the plat leaf shapes by using space curve theory. Different types of leaf shapes can be obtained by adjusting the parameters, and with the increase of leaf outline length parameters, leaves can grow. First, according to the characteristics of leaves, the curvature and torsion functions of the edge line can be determined, then the outlines of half leaves are drawn by solving the basic equations of space curves, and the other half edge of line is drawn according to the symmetry of the leaves. The curves of the main venations can be determined by using projection method and affine transformation. Loop subdivisions have been used to obtain smooth leaves. In the situation that the curvature functions are piecewise power functions, the growths of two-dimensional leaf blades are always along the axils of initial directions have been demonstrated. Using the method mentioned in this paper can draw out complex leaves. The simulation experiment results verify the feasibility of the proposed method.