Dietary lipids play an important role in human health, but their influence on aging and longevity remains to be ascertained. This study tests the hypothesis that the consumption of fats with elevated unsaturation might slow down aging and prolong lifespan better than that with greater saturation. The metabolomic analysis of Caenorhabditis elegans (C. elegans) administrated with different dietary oils (palm oil, rapeseed oil, sunflower oil and linseed oil) revealed novel changes in lipid, carbohydrate, amino acid and purine metabolism. Elevated levels of eicosanoic acid, stearic acid, palmitic acid, L-isoleucine, L-lysine, L-tyrosine, and D-fructose, along with decreased content of arachidonic acid (ARA), eicosapentaenoic acid (EPA), and alpha-linolenic acid (ALA) were found in C. elegans with the intake of dietary oils with higher saturation. Declined gene expression levels of daf-2 and akt-1, as well as increased levels of daf-16, sod-3, hsp-16.2, hsf-1, nhr-80, fat-5, fat-6, and fat-7, were noted in the higher unsaturation dietary oil groups. Carbohydrates and amino acids showed moderate to strong correlations with daf-2 and akt-1 (negative), as well as daf-16, sod-3, hsp-16.2, and hsf-1 (positive). Otherwise, our data suggested significant positive relationships between polyunsaturated fatty acids (ARA, EPA, ALA) and nhr-80, fat-5, fat-6 and fat-7. Taken together, this study demonstrates that unsaturated dietary oils can slow down aging and prolong the lifespan of C. elegans via the insulin signaling pathway and the biosynthesis of unsaturated fatty acids.