The oxidation of cholesterol in tallow heated at three frying temperatures, 130, 150 and 18$0^{circ}C$ was studied by assaying cholesterol oxidation products(COP)by GC-MS. The correlation between levels of COP and changes of physicochemical parameters (peroxide value, polymer, polar components and dielectric constant) in tallow heated were studied. As temperature increased, the amount of cholesterol was decreased proportionally with heating time. However, the levels of COP did not increase considerably with increased frying temperature. The rate of cholesterol disappearance was the greatest at 18$0^{circ}C$ and the smallest at 13$0^{circ}C$. Larger amounts of COP formed were found at 15$0^{circ}C$ than at 18$0^{circ}C$. The levels of COP formed in tallow heated showed highly correlation with(r=0.94, n=30, p<0.01) polymer, polar components and dielectric constant, respectively.