A series of ZrO2-TiO2-Al2O3 composite oxides with different Al2O3 ratios were prepared by coprecipitation method and used as the supports of Pt/NiO-MoO3/ZrO2-TiO2-Al2O3 catalysts. Catalytic activities for n-decane cracking over these catalysts were evaluated under high temperature and high pressure conditions. Physicochemical characteristics of as-prepared catalysts were detected by using automatic adsorption instrument, X-ray diffractometer, temperature programmed reduction, and temperature programmed desorption techniques to characterize the catalysts and supports. The results indicated that the catalyst which contained 60 wt % Al2O3 had the largest surface area and pore volume (152.7 m(2)/g and 0.39 mL/g, respectively), and also it possessed strongest medium and strong acidity as well as medium acidic density. Moreover, the catalyst with 60 wt % Al2O3 exhibited better cracking performances compared with the others. The gas yields over Cat3 were 1.5 and 1.2 folds higher than that obtained from thermal cracking at 650 and 700A degrees C, respectively. In addition, the heat sinks were improved 0.27 MJ/kg and 0.25 MJ/kg at 650 and 750A degrees C, respectively.