The invention provides a making method of pitaya fermented jam. According to the making method disclosed by the invention, pomace by-products produced in the processing course of a pitaya fermented beverage are processed for the second time, so that the production cost can be effectively reduced, waste of resources can be reduced, the processing industry chain of potayas is extended, and the sustainable development of the pitaya processing industry can be effectively promoted. The making method of the fermented jam provided by the invention is simple and practical and is suitable for industrialized production. The jam made by the method is rich in nutrients; and compared with jam processed from fresh pitaya fruits, the jam made by the making method is rich, fine and smooth in mouth feel, fragrant, sweet and palatable, slight in fermented delicate fragrance, and free from addition of chemical preservatives, and has broad market prospects.