The objective of this study is to quantify resource utilization of main predatory arthropods in integrated rice-duck farming system and to explore their role in resource allocation. Through field investigations on main predatory arthropods in integrated rice-duck farming and conventional rice cultivation systems, the structure of the predatory arthropods communities and their niches were explored. The quantitative distribution characteristics of each group in resource sequence and the condition of resource utilization were analyzed. Dominant species of predatory arthropods in the integrated rice-duck farming system and conventional rice cultivation system were Erigonidae, Araneidae, Lycosldae and Tetragnathidae, of which the dominance index of Araneidae was the greatest, accounting for 0.49 and 0.66, respectively, in the two cultivation systems. Foraging ducks in rice cropping field directly or indirectly influenced the number and distribution pattern of main predatory arthropods, thus leading to various degrees of changes in temporal-spatial dimensional niche breadth, niche overlap index and the niche proportional similarity. Temporal-spatial dimensions niche breadth of Erigonidae, Araneidae and Tetragnathidae were lower than those in the conventional rice cultivation system. The niche overlap indices of Erigonidae and Theridlidae, Tetragnathidae and Salticidae, Salticidae and Clubionidae, Clubionidae and Coccinellidae in the integrated rice-duck farming system were between 70.65% and 75.57% higher than those in the conventional rice cultivation system. Although the total individual numbers of predatory arthropods in the rice-duck farming system was 19.56% lower than those in the conventional rice cultivation system, group competition in the same resource sequence among main predatory arthropods became more intensified and time synchrony in resource utilization was more pronounced, which meant that predatory arthropods could make the best use of more potential resources in a more uniformed distribution and have a stronger controlling effect on pest population by longer occurrence time and continuous controls.