On 11 December 2019，the WTO Appellate Body （AB） stopped functioning de facto for lacking of sufficient AB members，which made the future of trade dispute settlement under WTO system uncertain. To respond to this crisis，the EU brought forward several plans at different levels. While trying to reform and save the AB，the EU proposed ad hoc appeal arbitration arrangement which was designed to maintain the major characteristics and advantages of WTO trade dispute settlement mechanism. In addition，the EU tried to protect its economic interests derived from international agreements by unilateral legislative measures. In general，the EU’s responding measures to the WTO AB’s lockout are by far the most comprehensive among stakeholders，however，the EU’s efforts are still insufficient to solve the fundamental crisis of the AB. On the one hand，it is unsure if the ad hoc appeal arrangement will be well accepted or be effective，on the other hand，the EU’s unilateral measures may cause new conflicts with its trade partners.