Abstract: In present study, SNP of prolactin(PRL) gene intron 1 of Gaoyou duck were detected by PCR-RFLP and DNA sequencing. The correlation analysis between the polymorphism of PRL gene intron 1 and egg-laying traits was carried out. The results indicated that there were two Dra I digestion sites in intron 1 of PRL gene, but only one was polymorphic. A T/C mutation at the position of the 1 326 bp of the PRL gene was found by DNA sequencing, and resulted in 3 genotypes (AA,AB and BB). The frequencies of genotype BB and allele B were the highest. The least square analysis showed that the BB ducks had higher egg weight at the age of 30 weeks than AB ducks (P<0.01), the proportion of double-yolk of the AB ducks was higher than that of BB ducks (P<0.05), but there was not significant difference in egg number, the longest days of continual laying and the body weight at first laying egg among 3 genotypes.