Aiming at the problems such as insufficient inter-domain collaboration ability， heterogeneous resource identifiers and low detection efficiency in conflict detection of cross-domain defense strategies in programmable networks， a cross-domain defense strategy conflict detection method based on multi-domain policy graph was proposed. Firstly， an intent-driven defense strategy model was constructed on the basis of the general JSON language， and the precise association between defense intentions and defense strategies was achieved through semantic label injection， so as to solve closed problem of the single-domain strategy model. Secondly， the Layered Hash Mapping （LHM） algorithm was utilized to generate Global Resource Identifier （GRI）， thereby solving the problem of resource identifier conflicts in multi-controller domains. Finally， by constructing a Multi-Domain Joint Policy Graph （MD-JPG）， as well as integrating the topological， action and resource dependencies among cross-domain strategies， a Cross-domain Conflict Detection algorithm based on graph traversal in four Dimensions， （CDC-4D） was designed to identify action conflicts， rule coverage conflicts， resource competition conflicts and strategy type conflicts accurately. Experimental results show that in the multi-controller network defense scenarios， the strategy conflict detection latency， memory usage， and detection F1-score of the proposed method have achieved good results.