In the era of the digital economy, digital transformation (DT) has become a new approach for firms to gain competitive advantages in a context of intense and dynamic market competition. Companies in almost all industries have undergone or are currently undergoing DT. Due to limited resources and capabilities, the digitalization process of small and medium-sized enterprises (SMEs) is relatively slow, so it is critical to ascertain the key factors and paths that affect the success of DT for SMEs to optimize the allocation of resources. However, there is very little research on the DT of SMEs. In response to this literature gap, the purpose of this study is to discover the key factors of the DT in SMEs and explore their interaction mechanisms. From a holistic perspective, this study has identified six key factors from three dimensions of technology, organization, and environment, and based on the resource-based view and resource-dependence theory, constructed an action mechanism model. Structural equation modeling was used to analyze the data collected from 180 SMEs in China. The results show that technological and environmental factors have a positive impact on organizational capabilities, and then promote the success of DT of SMEs. Organizational capabilities play an intermediary role in the influence of technological and environmental factors on DT. In addition, employee skills positively moderate the relationship between organizational capabilities and the success of DT. This study contributes to the conceptual framework and management implications in the DT field. Our study provides practitioners with profound insights into the enterprise’s DT and suggests that enterprises attach importance to the improvement of organizational capabilities, and use strategy and talents as important resources to promote the success of enterprise DT.