Cyber threat intelligence sharing enables organizations to gain stronger cyber security defense capabilities with less security investment. However, how to motivate organizations to share more threat intelligence information is a challenge. In this paper, cyber threat intelligence sharing is modeled as a cooperative game model, and a reward mechanism based on the shapley value is proposed. In this mechanism, we first introduced the concept of risk coefficient in cyber threat intelligence sharing, and improved the basic Shapley value benefit distribution mechanism to make the distribution of benefits fairer and more reasonable. Finally, the validity of the proposed model is verified by a case.