Blockchain is a powerful and distributed platform for transactions which require a unified, resilient, transparent and consensus-based record keeping system. It has been applied to scenarios like smart city, supply chain, medical data storing and sharing, and etc. Many works have been done on improving the performance and security of such systems. However, there is a lack of the mechanism of identity binding when a human being is involved in corresponding physical world, i.e., if one is involved in an activity, his/her identity in the real world should be correctly reflected in the blockchain system. To mitigate this gap, we propose BlockID, a novel framework for people identity management that leverages biometric authentication and trusted computing technology. We also develop a prototype to demonstrate its feasibility in practice.