Abstract:    Disruptive innovation is a process in which products or services based on new technologies are initially rooted in low-end markets or new markets, but as its performance improves, it attracts consumers and encroaches incumbents. This kind of strategic competitive behavior is generally valued by industrial practice, and it has also attracted increasing attention from research. Scholars have carried out a series of theoretical explorations around core issues such as the concept of disruptive innovation, behavioral characteristics, competitive strategies, market performance, innovation incentives, internal and external factors, and applied research in specific industries. However, as disruptors under the existing institutional arrangements, disruptive innovation companies often face the constraints of "legitimacy threshold". Innovation legitimacy is a generalized perception or assumption that the innovation actions of an entity are desirable, proper, or appropriate within some socially constructed system of norms, values, beliefs and definitions, emphasizing stakeholder value judgment. Disruptive innovation conflicts with existing technological paradigm, institutional logic and social norms, while different value judgments among stakeholders lead to serious material interest, spiritual value and moral norm value conflicts, which impede disruptive innovation legitimacy.
    Existing research still has the following deficiencies on disruptive innovation legitimacy: Firstly, although many scholars have amply analyzed theoretical cognizance, operating mechanism, entry channels and implementation paths about disruptive innovation, these studies rarely involve stakeholder conflicts caused by disruptive innovation. Secondly, most previous innovation legitimacy research is based on institutional and strategic perspective, lacking stakeholder evaluation to explore innovation legitimacy; moreover, most of these research focuses on project development environment conflicts, organization internal conflicts, team conflicts and entrepreneur-investors conflicts etc., lacking stakeholder value conflicts about disruptive innovation. Thirdly, existing studies have discussed definition, source, classification, acquisition methods about legitimacy and the impact on corporate performance, but these studies are mainly based on static perspective, lacking dynamics. Disruptive innovation surpasses social public level of recognition and acceptance, and the relationship between stakeholders of disruptive innovation is difficult to maintain in a stable state for a long time, so it is necessary to study deeply the stakeholder dynamic evolutionary relationship. 
    According to above research, and based on the development history of Didi Chuxing from 2012 to 2019, this study adopts the single-case longitudinal research method to investigate stakeholder value conflicts, legitimacy requirements and legitimacy acquisition strategies in different periods, and constructs a dynamic evolution theoretical model about disruptive innovation legitimacy. 
    The findings of this paper as follows: Firstly, disruptive innovation legitimacy presented as a complex dynamic evolution process of stakeholder value conflicts, and the degree of value conflict is different. During the periods of market entry, disruption and expansion, it mainly experiences the dynamic evolution of stakeholder spiritual value, material interest and moral norm value conflicts. Accordingly, the legitimacy requirement mainly goes through the dynamic evolution of cognitive, regulatory and normative legitimacy, and innovator mainly adopts selection, control and compliance strategies to gain legitimacy.
   Secondly, stakeholder value conflict of disruptive innovation is the driving mechanism for the dynamic evolution of innovation legitimacy. In the interaction with stakeholder behaviors, it will trigger new rounds of stakeholder value conflicts and actions, so that stakeholders will continually make new value judgments, and coordinate constantly the value conflicts among disruptive innovation stakeholders.  
    Thirdly, stakeholder value conflict of disruptive innovation is the market selection mechanism for the dynamic evolution of innovation legitimacy. Disruptive innovation stakeholder value conflicts reflect stakeholder value demands and the degree of resistance, guiding market value discovery and market selection in low-end or emerging markets, which lay market foundation to disrupt incumbent market.  
   Fourthly, stakeholder value conflict of disruptive innovation is the diffusion mechanism for the dynamic evolution of innovation legitimacy. Disruptive innovation leads the whole society continuously adjust recognition and acceptance, which promotes society reaching a new technological levels and institutional scenarios, so that disruptive innovation obtain legitimacy in neo-institution environment. 
    Finally, this study provides firms certain practical references for dealing with stakeholder value conflicts during the development of disruptive innovations. In addition, this study also provides government policy references for governing stakeholder value conflicts caused by disruptive innovation. 

Key words:  disruptive innovation legitimacy, value conflict, legitimacy acquisition strategy, dynamic evolution