The invention relates to papaya and mango low-sugar composite jam and a preparation method, and belongs to the technical field of food processing. The papaya and mango low-sugar composite jam comprises the raw materials in parts by weight of 10-30 parts of papayas, 20-50 parts of mangoes, 5-15 parts of glucose, 1-5 parts of xylitol, 0.1-1 part of carrageenan, 0.1-1 part of xanthan gum and 0.1-1 part of citric acid. The preparation method comprises the steps of preparing mango jam, preparing papaya jam, mixing the papaya jam with the mango jam, performing homogenizing, adding sugar for mixing,adding a thickening agent, performing concentration, performing canning and sealing, performing sterilization, and performing cooling. The papaya and mango low-sugar composite jam prepared by the method is orange in color, free from impurities, uniform in jam body, moderate in glutinous degree, free from the dehydrating phenomenon, slow in scattering, fine and smooth in mouth feel, and moderate insour and sweet taste, the original flavor and the nutrient value of the papayas and the mangoes are well reserved, and the papaya and mango low-sugar composite jam is hygienic and high in safety.