The potential anti-competitive conducts and antitrust risks associated with digital currencies are discussed in this paper. Based on the source of credit, digital currency could be distinguished as cryptocurrency and central bank digital currency. The cryptocurrencies could be further divided into public chain digital currency and consortium chain digital currency. The research shows that: for cryptocurrency, the blockchain of the public chain digital currency is "decentralized". However, its endogenous mechanism may induce the concentration of computing power and may further raise the risks of collusion among the mining pools. The blockchain of consortium chain digital currency is maintained by a few verification nodes, which obtains certain risk of collusion inherently. Some nodes may also foreclose other digital currencies and payment channels by leveraging their market dominance. Given that both the mining pools and verification nodes are located across the globe, the potential collusions may constitute significant challenges for the current fragmented antitrust enforcement system. For central bank digital currency, central banks may implement administrative monopoly behavior in four aspects: architecture, infrastructure, access technology and interconnection. To enhance DC/EP’s competitiveness and secure prosperousness of China's digital currency industry, People’s Bank of China should uphold the principle of both competition neutrality and technology neutrality.