The invention discloses a modified top grafting method of scion grafting of cortex jatrophae and belongs to the technology field of plant grafting. The method is preferably performed during the second third of February to the last third of March or the first third of September to October, at a mean daily temperature up to 20 DEG C plus or minus 3. A wedge-shaped grafting scion with 2-3 axillary buds is cut from a lignified or semi-lignified twig of good-quality cortex jatrophae, and the scion has a long inclined plane of 3-4cm and a short inclined plane of 2-3cm, and the two inclined planes are cut smooth and flat at the same time. A notch of 2-4cm is cut on a smooth stock and the notch is perpendicular to a part of xylem at the inner side of the cambium layer. After the sap of the scion and the stock is drained after the stock cutting, the grafting scion is inserted into the notch in a way that the cambium layers of the stock and scion are partially fitted at one side, and the grafting scion, the grafting cut and the stock cut are bound for seal, followed by timely examination and graft supplementation. After the graft survives, the bondage is removed and the stock bud is erased for several times, thereby promoting survival. The survival rate of cortex jatrophae grafted by the method is high up to over 98%.