Although the online retailing of proprietary trading has achieved great development in the Internet context, it still faces many pains and bottlenecks. Therefore, it is of theoretical and practical significance to explore how the online retailers of proprietary trading to perform commercial capital functions. Different from the early stage of e-commerce, digitalization makes it much possible for online retailers of proprietary trading to break through traditional profit dilemma and get rid of the single platform orientation, then return to proprietary trading and finally enhance circulation efficiency. To reveal how the online retailers of proprietary trading realize digitalization upgrading, this paper first summarizes the essence of the online retailers of proprietary trading and the possible path of digitization from a theoretical perspective. Then, two typical cases are selected to depict a more complete internal mechanism. Research shows that with digital technology, the online retailers of proprietary trading can not only enhance the efficiency of commodity operation through strengthening the function of commercial capital, but also attain the synchronous improvement of circulation and production efficiency through the reverse integration of supply chain. Meanwhile, enterprises can accelerate the market expansion and improve the efficiency of physical stores by digital empowerment. The above mechanism provides some inspiration for the online retailing of proprietary trading and its digital retail innovation.