Mars Ecosystem is a new decentralized Stablecoin paradigm that addresses the fundamental issue of Stablecoin Protocols, known as the Positive Externality Problem. It accomplishes this by internalizing the positive externality, integrating the creation and use of stablecoin within a single ecosystem. The relationship between Mars Stablecoin and Mars DeFi primitives forms a positive feedback loop, resulting in a flywheel effect. The stability and liquidity of Mars Stablecoin are supported by the Mars Ecosystem Token (XMS) and the Mars Treasury, which is funded with various cryptocurrencies. In addition to integrating with existing DeFi protocols, Mars Ecosystem introduces Mars Swap, Mars Stableswap, and Mars Money Market to provide value to Mars Stablecoin users and XMS holders. XMS holders possess governance rights and manage the Mars Treasury. They can also stake XMS at the DEX to earn a portion of the transaction fees generated. Mars Swap functions as a Uniswap-type AMM DEX, offering deep liquidity between Mars Stablecoin and all other tokens.