The invention relates to a 1,8-naphthalimido heterocyclic azo disperse dye and a preparation method therefor. The 1,8-naphthalimido heterocyclic azo disperse dye is prepared from two parts, i.e., a diazo component and a coupling component, wherein the coupling component is a heterocyclic active methylene compound or heterocyclic phenolic compound which is coupled under alkaline conditions, and the diazo component is alkalescent heterocyclic arylamine or an alkalescent aniline derivative. The preparation method comprises the steps of carrying out diazotization on the alkalescent heterocyclic arylamine or alkalescent aniline derivative in an organic solvent in the presence of a stabilizer so as to separate out stable diazo salt solids, carrying out filtering to obtain solids, and then, applying the solids to alkaline coupling, thereby obtaining the target dye. The dye can be applied to the dyeing of polyester fibers, polyamide fibers, polylactic-acid fibers, polypropylene fibers and acetate fibers and has excellent dyeing brightness.