In this study, the thermal stability of palm frying oil (palm stearin, POs) and a formulated high oleic frying oil (high oleic blended oil, HOBO) in China was evaluated under simulated frying protocol in fast food restaurants. A series of physico-chemical properties of the oils were measured including change of colour, acid value (AV), peroxide value (PV), p-anisidine value (p-AV), total oxidation (TOTOX=2PV+p-AV), fatty acids composition (FAC), iodine value (IV), carbonyl group value (CGV), total polar compounds (TPC), oxidative stability index (OSI) and vitamin E content. The frying experiments were conducted at 170 ± 5°C for five consecutive days where French fries were fried in five cycles hourly for 12 hr a day. The results indicated that POs gave higher physical and chemical stability than HOBO under extended frying conditions, considering its relatively lower increase in TPC, p-AV, TOTOX and CGV, lesser decrease in C18:2/C16:0 and IV, and longer induction period. Based on the results, it can be conjectured that POs is a more preferred choice for deep fat frying with lower deterioration rate.