Aim To investigate difference expression of peroxisome proliferator-activated receptor α (PPAR α) during aging and explore the molecular mechanism of perturbation in lipid metabolism during aging. Methods We used two-group SD rats to estimate the lipid level of young (6～8 weeks) and aged (24 months) groups. The levels of triglyceride (TG) and total cholesterol (TC) were examined. The levels of liver PPAR α and target genes mRNA were measured by reverse transcription-polymerse chain reaction (RT-PCR) and PPAR α protein were determined by western blotting respectively. Results The TG and TC level of the aged group increased significantly. The PPAR α mRNA and protein level of the aged group significantly decreased compared with the young group. Target gene levels were changed during aging. Conclusion The mechanism of lipid dysfunction during aging is probably associated with the decreased expression of PPAR α.