Abstract In this experiment, the direct aldol reaction between unmodified acetone and 4-nitrobenzaldehyde catalyzed by L-proline shows both high yield and moderate stereoselectivity. The mixture was stirred at room temperature over a period of 2 hours. The pure product was obtained by column chromatography on silica gel and the enantiomeric excess of the product was determined by chiral HPLC analysis. The product yields obtained by the students are about 53%~74%, and the values of ee are about 62%~69%. This comprehensive experiment can not only strengthen the basic synthetic skill and operation, but also broaden the knowledge and cultivating the ability of analyzing and solving problems.