Abstract:      With the increasingly complex and changeable internal and external environment of the organization, the dissemination of crisis information has the characteristics of diffusion and openness. The frequency of crises ranges from accidental to normal, from original to derivative. A crisis event may trigger a series of secondary crises, making it difficult for enterprises to repair crisis. For example, the new mobile phone products launched by Samsung caused accidental explosions due to hidden battery safety problems. The rapid spread of the incident through the media and public opinion seriously affected the normal sales of other series of the brand. For example, Toyota was also reported by the media for airbags. There are flaws and they are collectively questioned by the public, and the public trust in the brand has dropped sharply. Sudden crisis events not only cause huge damage to the operation capacity of enterprises, but also have incalculable negative effects on the reputation and image of enterprises. The COVID-19 epidemic crisis has made it difficult for many companies to maintain normal business activities, and some even face bankruptcy crisis, which is undoubtedly a huge test for enterprises. How to quickly respond to sudden changes and solve the crisis repair problem has attracted great attention from the academic and practical circles. Based on the perspective of organizational improvisation, this paper took Yili Group as the case study object, analyzed its behavior characteristics in the face of COVID-19 epidemic crisis and melamine crisis, explored how enterprises carry out organizational improvisation activities under the crisis situation based on organizational improvisation theory, and revealed the realization mechanism of enterprise crisis repair.
      The findings of this research are as follows: firstly, crisis pressure is the key incentive to stimulate enterprises to take organizational improvisation and realize crisis repair, which induces enterprises to promote the realization of crisis repair through the synergy of "letting go" and "making do". The "letting go" and "making do" reflect the organizational improvisation process of enterprises, which is the concrete embodiment of impromptu behavior. Under the crisis situation, enterprises are faced with great uncertainty. Through the cooperation of "letting go" and "making do", strategies can be adjusted in time according to the situation changes to make up for the gap between the plan and the special situation solutions.
        Secondly, the "letting do" is the microscopic mechanism for enterprises to realize crisis repair, which embodies the realization mechanism of organizations understanding and internalization of situations and is the logical basis for enterprises to carry out actions. Organizational crisis is highly uncertain, and the situational changes it brings make it impossible for enterprises to take response measures according to organizational practices. Under this background, enterprises can respond immediately to the situation changes brought by organizational crisis through the attention allocation process of "perception-attention-judgment".
     Thirdly, the "making do" is driven by managers′ cognition is the key link for enterprises to realize crisis repair, and it constructs a new resource framework through creative activities to adapt to the situation changes and realize crisis repair. Under the pressure of crisis, enterprises will form brand-new cognitive patterns for different concerns according to the changes of external dynamic situations, implement differentiated resource arrangement activities, effectively integrate the resources of enterprise departments and carry out innovative activities to restore the normal operation state and relationship state so as to repair the crisis.
    This paper discussed the process of organizing impromptu crisis repair through case analysis. Firstly, this study enriches the research perspective of crisis repair mechanism. Secondly, it perfects the concrete behavior connotation of organization improvisation. Finally, this study expands the situational analysis of organizational improvisation research. This paper reveals the changing process of enterprises cognition and action in crisis situation so as to clarify the internal mechanism of enterprise crisis repair based on organizational improvisation, perfect relevant theories of organizational improvisation, guides enterprises to quickly seize market opportunities and grow up in crisis situation, and provides theoretical and practical enlightenment for enterprises to deal with crisis events. In terms of management practice, enterprises need to update their decisions in real time according to the changes of situations in crisis situations，so as to guide themselves to integrate and utilize resources effectively, carry out innovative activities and make up the gap between strategies and situations in a timely manner in order to quickly mitigate the impact of the crisis on enterprises.

Key words: crisis repair, organizational improvisation, letting go, making do