Abstract: The aim of this study was to obtain the information about sequence structure, tissue expression and biology function of porcine NAP1L5 gene. In the present study, the porcine NAP1L5 was cloned by RTPCR, the sequence was analyzed by bioinformatics method, and its relative mRNA expression was detected by quantitative RTPCR in porcine placenta at different gestation stages. Sequence analysis showed that the CDS region of the porcine NAP1L5 gene included 579 nucleotides, encoding 193 amino acids, and the sequence similarity of NAP1L5 between the pig and cattle was 89%. The amino acids sequence included the nucleosome assembly protein. The result of quantitative RTPCR indicated that the expression of porcine NAP1L5 increased with the placenta development and there were significant difference between d26 and d50 of gestation stage (P<0.01). These results suggest that NAP1L5 is probably related to the nutrition absorption and early development of porcine fetus, and make a foundation for the further study on the function of NAP1L5 gene in porcine.