Metal-modified molecular sieves (MAPO-5, M=Co, Mn, Fe) have been hydrothermal synthesized and investigated in the selective oxidation of p-tert-butyltoluene (PTBT) to p-tert-butyltolualdehyde (PTBD). CoAPO-5 exhibited the best catalytic activity. Under the optimized conditions: reaction time 6 h, PTBT 5 g (33.7 mmol), CoAPO-5 0.3 g, tert-butyl hydroperoxide 12.2 g (134.8mmol), acetonitrile 18 mL, reaction temperature 70 ℃, the conversion of PTBT reached to 15.5% with a PTBD selectivity of 73.4%. Recycle runs suggested that CoAPO-5 was stable for at least 5 cycles without obvious changes of catalytic activity and selectivity.