Objective  To optimize the chromatography colorimetry method and verify by analytic methodology, to compare optimized chromatography colorimetry with chromatography integration, and to evaluat the applicability of the two methods to determine the molecular size of typhoid Vi refined polysaccharide. Methods  The concentration range of O-acetyl standard curve of colorimetry was optimized, and its accuracy, repeatability, intermediate precision, linearity and durability were verified. The molecular size of multiple batches typhoid Vi was tested using chromatography colorimetry and chromatography integration, and the results were statistically analyzed. Results  The accuracy recovery rates of the optimized chromatography colorimetry were all 100%. The relative standard deviations（RSDs) of corresponding repeatability of samples were both＜5.0%, the RSDs of intermediate precision were both 3.4%. The standard curve was analyzed for 5 time, and coefficients of determination were all greater than 0.9990. The RSD of durability was 4.6%. There was no statistically significant difference between optimized chromatography colorimetry and chromatography integration in the detection of molecular size of typhoid Vi refined polysaccharide (t=-1.372, P > 0.05). Conclusions  The optimized chromatography colorimetry has good accuracy, repeatability, intermediate precision, linearity and durability. Both methods are applicable in detecting the molecular size of typhoid Vi refined polysaccharide.