From the Free Software Movement led by Richard Stallman, to The Cathedral & The Bazaar written by Eric Raymond, to Mozilla and Linux, as well as recent blockchain open source projects such as Ethereum, open source(OS) has steadily empowered the whole society and brought us today's digital infrastructure with low cost and flexible customization. Although OS is used everywhere, it is ignored that maintaining OS requires enormous energy and time from developers who usually spend their spare time contributing to the OS. Typically, developers are financially motivated to build and maintain OS (whether via direct payment or building reputation and skills for future work)\. However, open source software(OSS) developers have not always been properly incentivized for their input. A survey of 400 developers conducted by Tidelift shows that 46% of open source contributors don't get paid, and 26% of them earn just over $1,000 a year. The lack of proper and sustainable incentive mechanisms leads to code errors, security vulnerabilities, service outages and a lack of continuous maintenance, like the Heartbleed bug of OpenSSL in 2014. Therefore, how to motivate the developers over the long term is the key to the development of OSS.