OBJECTIVE： To improve the synthesis technology of sodium picosulfate. METHODS： The synthesis technology of sodium picosulfate was improved by changing reaction solvent， charging sequence， refined method and formation of crystal water. Using phenol as raw material， it was condensed with 2-pyridinecarboxaldehyde to achieve 4，4′ -（pyridin-2-ylmethylene） diphenol， and its yield rate was investigated. Sodium picosulfate was obtained after esterification， salification， formation of crystal water， and then its purity was determined. RESULTS： The yield rate of key intermediate 4，4′ -（pyridin-2-ylmethylene） diphenol reached above 88％， and the purity of refined products reached over 99.5％. Sodium picosulfate monohydrate was stable， and the content of single impurity was less than 0.1％. CONCLUSIONS： The improved technology is simple with mild conditions， and suitable for large-scale production.