The invention mainly relates to a method for preparing pure peony seed essential oil soft capsules. The method comprises the steps that 1, peony seed essential oil is extracted in a supercritical extraction mode; 2, ultraviolet light disinfection and sterilization are conducted on the peony seed essential oil obtained in the step 1; 3, after sterilization is conducted for 1h-3h, the peony seed essential oil is transferred to a sterile low-temperature constant-temperature stirring container; 4, the peony seed essential oil is stirred at the temperature of no more than -10 DEG C until the peony seed oil is thoroughly condensed; 5, capsule filler is prepared; 6, capsule shells containing xylitol are prepared and the capsules are filled in a solid extruding mode. According to the preparing technology, the filler of the soft capsules is frozen and condensed, filling is conducted in a solid mode so that the phenomenon that when filling is conducted in the liquid state, the filler overflows and resources are wasted can be avoided, and the phenomenon that the overflowing filler adheres to a surface layer of each capsule shell and the steps of cleaning and drying are needed after pressing of each capsule is completed can be further avoided, and therefore the technical steps are saved and the production cost is reduced. When the capsule shells are prepared, the xylitol is added, so that the capsule shells are good in taste. In addition, the xylitol can prolong the service life of the soft capsules and improve the quality of the soft capsule product.