The invention relates to a preparation method and a preparation device of edible blending oil and in particular relates to a preparation method of peony seed blending oil with a lipid-lowering health-care effect as well as a cold oil press for preparing the peony seed blending oil. The preparation method comprises the following steps: performing pretreatment comprising shelling and kernel-shell separation, on peony seeds, pressing the peony seeds obtained through the kernel-shell separation, performing one-step pressing during pressing, adding distilled water into the obtained oil residues, heating, performing ultrasonic shaking centrifugal treatment, sequentially adding water, heating and performing ultrasonic shaking centrifugal treatment, obtaining coarse oil, purifying the coarse oil, and finishing the pressing process. In the process flow, the used cold oil press comprises a feeding hole, a pressing chamber, a residue discharge channel, an oil outlet and a power device, and also comprises a centrifugal pan, an oil filter cover, a heating device, an ultrasonic source, an oil groove and an oil-water separation chamber. The peony seed blending oil prepared by the method is low in price, has effective lipid-lowering health-care effects during long-term eating and accords with the diet concept of modern people.