To engineer Yarrowia lipolytica for improving the heterologous production of campesterol (a key precursor to manufacture pharmaceutical steroids). By screening 7-dehydrocholesterol reductase (DHCR7) from diverse species, DHCR7 from Danio rerio was the best candidate for campesterol synthesis. Overexpression of ACL (ATP: citrate lyase) or POX2 (peroxisome acyl-CoA oxidase 2) were key to improving campesterol production. The highest yield of campesterol was 942 mg/l was with the strain overexpressing POX2 in a 5 l bioreactor via high cell density fermentation process with a restricted supply of carbon sourc, sunflower seed oil. A promising platform to synthesize downstream steroid drugs was established. Efficient approaches were provided to improve the production of desired molecules in Y. lipolytica with high oil utilization efficiency.