Organizational resilience is a key factor for the longevity of an organization. In the face of a major public health emergency, it is worth studying the approaches to improve the organizational resilience of enterprises. Based on the principal-agent theory and resource allocation theory, this article deeply analyzed the process and mechanism of diversified operation affecting organizational resilience in the context of the COVID-19 pandemic. The results show that diversified operation has a significant negative impact on its resistance dimension of organizational resilience while has no significant effect on the resilience dimension. Furthermore, the negative influence of diversification on organizational resilience is only significant in non-state-owned enterprises.