The invention relates to a fluffy granular composite sugar-free table sweetener and a preparation method. The sweetener comprises the following components: 20-30% of xylitol, 20-35% of erythritol, 35-55% of isomaltooligosaccharide and 0.8-1.2% of sucralose. The process comprises the following steps: respectively adding 8% of isomaltooligosaccharide and the sucralose to a heating container and respectively adding deionized water for mixing; raising the temperature until dissolution; adding activated carbon to the solution respectively, filtering the mixture while the mixture is hot and collecting the filtrates respectively in storage tanks; and pumping the ground mixture of the xylitol, the erythritol and the isomaltooligosaccharide into a fluidized bed with spraying from the bottom of thebed under positive pressure and ensuring the mixture to flow at high speed from bottom to top, applying negative pressure to the upper part of the fluidized bed with spraying so that the bed vibratesfrom top to bottom to ensure the materials to boil in the bed; using a multipoint spray gun at the side of the fluidized bed to continuously spray and disperse the refined sucralose solution on superfine sugar alcohols, then pumping the isomaltooligosaccharide solution and carrying out continuous spray drying, thus obtaining the sugar-free table sweetener. The preparation flow is simple and convenient and the sweetness of the product is 5-10 times that of the common sucrose.