Abstract: Cross regional public emergency is a new type of public crisis, and improving the horizontal government coordination legal system is the basic way to deal with the cross regional public emergencies in the future.At present, there are some problems in the governance of cross regional public emergencies, such as the relatively weak concept of emergency, the dispersion of emergency subjects, and the fragmentation of emergency resources.Among them, the root cause is insufficient legal supply,it is mainly manifested in the following aspects:the coordination mechanism between governments is not perfect, the effectiveness of emergency agreement is not perfect, the resource sharing mechanism is not smooth, and the interest compensation mechanism is not mature.Based on this, the state must strengthen the supply of legal system around the emergency response law, give local governments the right to coordinate in legislation and clarify the operating rules of intergovernmental coordination agencies; strengthen the construction of good faith and equal consultation, give the emergency agreement legal effect; improve the sharing mode of emergency resources among governments, and establish a cross regional resource collaborative allocation and emergency information sharing mechanism; respect the autonomy of the assistance subject, through the job assistance cost mechanism and the cross-regional emergency financial transfer payment mechanism to ensure the initiative and fairness of intergovernmental emergency assistance.