The first-strand cDNA sequence encoding pancreatic trypsinogen (TRY) gene was isolated from yellow catfish (Pelteobagrus fulvidraco) larvae (1-30 dph,day post-hatching) by RT-PCR,and using real-time PCR to detected and quantitated the trypsinogen gene expression.The results showed that the onset of trypsinogen gene expression in P.fulvidraco larvae was 1 dph and the trypsinogen gene expression increased significantly from 1 to 6 dph,increased fluctuantly from 6 to 23 dph and rose sharply from 23 to 30 dph.The experimental results demonstrated that the detection and quantitation of trypsinogen gene expression in P.fulvidraco larvae would accurately reflect the process that digestive functioning developed in intestinal tract.And we suggested that weaning time of P.fulvidraco larvae would be much better after 23 dph.