Unconventional emergencies impact the emergency management system and lead to a large number of unplanned behaviors. System learning is the key to improving the system resilience. This paper focuses on the response function of the joint prevention and control mechanism and the optimization of plan under the background of the Covid19 epidemic. By establishing the text database of joint prevention and control mechanism and carrying out content analysis, this paper sums up the functional perspective and characteristics of joint prevention and control mechanism in the real scene, and then compares it with the function design of the existing plan to reveal the difference between the reality and the text of the response function of emerging infectious diseases. It is proposed that the emergency response function should be expanded and refined according to the actual function needs of the emergency management of public health emergencies, so as to provide basic empirical support for the followup institutional learning, especially the optimization of the emergency plan.