The rise of BTC L2 is an undeniable narrative in the current cryptocurrency market. BTC L2 provides greater performance, programmability, and privacy capabilities than Bitcoin itself. This article introduces two main aspects: off-chain and enhanced capabilities, and, based on the underlying architecture's isomorphism, divides it into the UTXO camp and the EVM camp. It focuses on introducing the features, ecosystem development, and token economic model of the UTXO isomorphic BTC L2 project Nervos Network.