NEO is a non-profit, community-based blockchain project. It is a distributed network that uses blockchain technology and digital identity for asset digitization. It is also an intelligent management of digital assets using intelligent contracts to create “Smart Economy”. At present, NEO’s market capitalization ranks fifteenth in the world in coinmarket, being one of the remarkable blockchain projects. We found a Denial of Service vulnerability in the NEO smart contract platform which attacker could use to instantly crash the entire neo network.