The invention provides an improved belinostatsynthesis method. According to the method, sodium m-carboxyl benzenesulfonate is taken as a starting material, and belinostat is prepared through six steps of esterification, acylation and aniline condensation, reduction, oxidation, Wittig-Horner condensation and hydrolysis as well as acylation and hydroxylamine condensation. With the adoption of the method, the production time is shortened, the reaction yield is increased, the production safety is enhanced, the environmental pollution is reduced, and the method is more suitable for industrial production.