This article presents efficient syntheses of two labeled standards [13C6]leucocrystal violet and [13C6]violet crystal with 13CH3OH as the common substrate. Esterification of p-toluenesulfonyl chloride with 13CH3OH provided [13C]methyl p-toluenesulfonate, which was used to methylate aniline to give [13C2]N,N-dimethylaniline. Condensation of [13C2]N,N-dimethylaniline afforded [13C6]leucocrystal violet and [13C6]violet crystal. Both products were shown by NMR and LC-MS to be target compounds. Their chemical purities are higher than 99 % and isotopic enrichment are higher than 98.5 %.