The invention discloses a preparation method of N, N'-bis(2, 2, 6, 6-tetramethyl-4-piperidyl)-1, 3-benzenedicarboxamide which is represented by formula (I). The preparation method comprises following steps: (1) 2, 2, 6, 6-tetramethyl-4-aminopiperidine and m-phthalyl dichloride are taken as raw materials, and are reacted in an anhydrous organic solvent at a temperature of -5 to 25 DEG C until complete precipitation is realized, reaction liquid is filtered, and the filter cake is washed with the anhydrous organic solvent and dried so as to obtain an intermediate (II), wherein the anhydrous organic solvent is one selected from n-heptane, n-octane, petroleum ether, acetone or butanone; (2) at room temperature, the intermediate (II) is mixed uniformly with water, sodium hydroxide solution is added for neutralization, the mixture is filtered and washed with water so as to obtain a filter cake, and the filter cake is dried so as to obtain N, N'-bis(2, 2, 6, 6-tetramethyl-4-piperidyl)-1, 3-benzenedicarboxamide represented by formula (I). The preparation method possesses advantages of high product quality, simple operation technology, convenient operation process and high raw material utilization rate.