A series of NH4Cs1.5Fe0.08HxPVMo11AsaOy heteropolycompound catalysts for the selective oxidation of isobutane, having Keggin structure, were synthesized by using co-precipitation method. The catalysts were characterized by FT-IR, H2-TPR, TG-DTA, SEM and XRD. Effects of the As content,reaction time, reaction temperature and molar ratio of isobutane to oxygen in feedstock on the activity and selectivity of the catalyst were investigated. The activation energy of the catalysts was measured by kinetics researches. Results showed the introduction of Cs+ into the catalysts shortened the stable period of them and enhanced their catalytic activity for the selective oxidation of isobutane. The highest conversion of isobutane and the total selectivity to liquid products were 18.6% and 81.2%, respectively,which were obtained at 380 ℃ with a space velocity of 975 h-1 over the NH4Cs1.5Fe0.08HxPVMo11As0.3Oy heteropolycompound catalyst. It is confirmed that completely oxidized products were controlled well.