The invention discloses a dragon fruit jam and a preparation method thereof. The dragon fruit jam is prepared from the following materials in parts by weight: 100 parts of dragon fruit with peel, 60-65 parts of water, 5-15 parts of a 
sweetening agent, and 0.3-0.7 parts of a 
thickening agent. The preparation method comprises the following steps: removing thorns from the dragon fruit with peel, cleaning, 
slicing, 
grinding and stirring the dragon fruit to obtain dragon fruit pulp, completely dissolving the 
sweetening agent and the 
thickening agent, adding the dragon fruit pulp, uniformly stirring the pulp, conducting high temperature instant sterilization, cooling the sterilized pulp, then conducting 
fermentation treatment, and conducting 
microwave concentration, filling and ultrahigh pressure sterilization so as to obtain the dragon fruit jam. The dragon fruit jam disclosed by the invention is of a natural edible value and a natural medicinal value of the dragon fruit, is low in 
sugar content, and can keep the natural 
nutrition and the 
flavor in the 
raw material well by the adoption of the 
microwave concentration technology and the ultrahigh pressure technology.