A high performance liquid chromatographic assay has been developed for the simultaneous determination of four water soluble vitamins,thia min, ribo-flavin, uiacin and pyridoxine, in cereal products and fresh vegetables. For hydrolyzing sample in 0.4 mol/L HCL, autoclaving at 120℃, 15 psi for 30 minutes, a ?Bondapak column (300mm ? 3.9mm, Waters Co), a mobile phase of methanol-water (30:70) (0.005 mol/L heptanesulfonic acid) and a flow rate of 1.0ml/min gave the most satisfactory separation of the four vitamins. A double channel detector was used: three vitamins (B1, B2 and B5) were detected by UV spectrophotometry (254 nm) first, pyridoxine (B6) was detected by fluorometry (EX 290 nm, EM 390 nm) afterwards. Detection limits were 2, 5, 5 and 2ng, linear ranges were 5-40 ng, 5-50 ng, 5-40 ng and 5-50 ng for B1, B2, B5 and Be, respectively. Recoveries were 91.3%-102% (B1), 103%-105% (B2), 92%-100% (B5) and 99%-100% (B6), comparing with reference method and checking with food composition tables, very satisfactory results were obtained by this method.