The invention discloses a preparation method of colorless fatty alkyl amphoteric sodium acetate. The method comprises the following steps: a) amidation reaction: dehydration reaction of fatty acid and excess hydroxyethylethylenediamine to generate amides; b) preparation of intermediates: Cool the prepared amide to cool down, add solvent and stir to dissolve, stir and cool down to crystallize, after the crystallization is completed, separate the solution from solid to liquid by vacuum filtration or centrifugation to obtain a filter cake, and vacuum dry to obtain the intermediate; c) Preparation of colorless fat Sodium alkylamphoacetate: add deionized water to the prepared intermediate, heat up, stir and dissolve fully, then add sodium chloroacetate solution and 32% liquid caustic dropwise at the same time, then heat up to 80-100°C, and then stir at a low speed. The color of the product prepared by the present invention is ≤30 Hazen, the residue of chloroacetic acid is ≤30ppm, the purity is high, the temperature is low, no precipitation occurs for a long time, the quality is stable, the process is reasonable, the steps are few, the energy consumption is low, the equipment investment is small, the process is simple, easy to operate, and the production low cost.