The invention relates to the technical field of fruit and vegetable preservation, and discloses a passionflower herb antistaling agent. The passionflower herb antistaling agent is prepared from, by weight, 20-100 parts of prochloraz and / or iprodione, 10-30 parts of butanediol, 1-5 parts of glycosyl trehalose, 0.1-1 part of sodium hyaluronate, 0.1-1 part of thickener, 5-10 parts of surfactant and 100-500 parts of water. The invention further provides a preparation method of the passionflower herb antistaling agent and a method for conducting preservation treatment on passionflower herb through the antistaling agent. The antistaling agent can significantly control epidermis shrinking and fruit rotting of the passionflower herb through a technology of combining sterilizing and moisturizing, the storage period and shelf life of the passionflower herb are effectively prolonged, and the commodity value and economic benefit are improved; meanwhile, by means of the antistaling agent and negative pressure or ultrasonic wave compound soaking treatment, chemical preservation and physical sterilization are compounded, safety is achieved, and toxicity does not exist. The preparation method of the passionflower herb antistaling agent is simple, efficient, safe and wide in application prospect.