The invention provides a processing method of nutritional frozen Hibiscus esculentus slice. The method comprises the steps of material selection, color protection, sterilizing (ozone combined with microwave), freezing (cooling, and ultrasonic-assisted freezing), thawing, preparing, screening, slicing, quick-freezing, packaging, sealing and delivering. The method provided by the invention adopts ultrasonic-assisted freezing to solve tissue structure disintegration problem in single freezing process, effectively promotes nucleation under simultaneous mass-transfer action and heat-transfer action of ultrasound, avoids damage of functional ingredients in Hibiscus esculentus, and avoids nutritional ingredients loss by adopting two-step operation of freezing and sterilizing. Under joint action of ozone and microwave in sterilization process, the method has thorough sterilization and obvious effect; in combination with sterilization with 75% ethanol, bacterial count can be controlled at 500-300 / g, sterilization time is shortened by above 30%, and the product is safe, pollution-free and residue-free.