The invention relates to phytoremediation technology for organic poison polluted soil, in particular to a method for restoring petroleum-polluted soil by utilizing an ornamental plant, namely morning glory. The method adopts the technical proposal that adequate sand is doped into the petroleum-polluted soil; morning glory seeds are soaked by distilled water until seed hulls are expanded and cracked, and subjected to spot seeding into petroleum hydrocarbon polluted soil; and the morning glory planted in the petroleum hydrocarbon polluted soil adopts outdoor planting and watering at a fixed period, and the water content of the soil is maintained to be 70 to 80 percent of the field capacity. Compared with the prior method for treating the petroleum-polluted soil, the method has the advantages of small investment, small engineering quantity, low technical requirements and so on, and can not cause secondary pollution, and simultaneously the restoring process not only can not damage the ecological environment of the soil but also helps to improve soil degradation and productivity reduction caused by petroleum hydrocarbon pollution and recover and improve the biodiversity of the soil.