The invention relates to a biodegradable antisludging inhibitor, namely an olefin-containing poly(aspartic acid) derivate and a preparation method thereof. The preparation method for the olefin-containing poly(aspartic acid) derivate comprises the following steps: (1) an aspartic acid is taken as a raw material and subjected to thermal polycondensation to generate polysuccinimide; (2) a sodium hydrogen aspartate solution is prepared; (3) an olefin-containing poly(aspartic acid) derivate aqueous solution is generated by utilizing aminolysis reaction; and (4) alcohol extraction, filtration and drying are performed. The olefin-containing poly(aspartic acid) derivate has the advantages that: due to introduction of an aspartic acid group in a poly(aspartic acid) structure of the olefin-containing poly(aspartic acid) derivate, the olefin-containing poly(aspartic acid) derivate improves the scale inhibition and dispersion capacities, and has good scale inhibition effect, good biodegradability and corrosion inhibition and strong heat resistance. The preparation method is simple. Moreover, the product can be widely applied in the aspects of circulating and cooling water systems, boiler water, oil field water, seawater desalination and so on.