The digital currency, led by Bitcoin and USDT, has the characteristics of decentralization and anonymity, which makes the identity of traders difficult to identify, thus providing a hiding space for illegal activities, such as drug trafficking, money laundering, cyber fraud, terrorism, etc. Focusing on the USDT-TRC20 token on the Tron blockchain, we propose a transaction tracing method to trace the transaction path for digging out hidden addresses and encrypted assets. Specifically, we first construct a two-layer transaction network, where the top layer network describes the flow of USDT-TRC20 between on-chain addresses over time, and the bottom layer network represents the flow of TRX between on-chain addresses over time. Secondly, we propose a digital token transaction tracing method based on the constructed two-layer transaction network to identify the hidden on-chain address and different addresses belonging to the same user or group. Finally, we describe the acquisition of transaction records queried from the blockchain browser, and then the validity of the proposed tracing method is verified by empirical data.