Abstract: 1H-NMR spectra were obtained with a Bruker AVANCEⅢ 400 MHz spectrometer at 298 K with maleic acid as intemal standard and D2O as solvent. For each sample, 16 times of sampling were recorded under the following conditions: the pulse sequence of zg30, acquisition time of 3.98 s, spectra width of 20.55 ppm and delayed time of 20 s.A linear relationship was found between the mass ratio of vitamin B1 with the internal standard and the corresponding ratio of quantitative peak areas. The proposed method was used to determine vitamin B1 in tablets, and the contents of vitamin B1 in vitamin B1 tablets and vitamin B complex tablets were 11.33% and 2.54%, respectively, with RSDs (n≥5) less than 4%. Recovery rates obtained by standard addition method were in the range of 97.4%-101%.