  Machine learning and blockchain are two of the most noticeable technologies
in recent years. The first one is the foundation of artificial intelligence and
big data, and the second one has significantly disrupted the financial
industry. Both technologies are data-driven, and thus there are rapidly growing
interests in integrating them for more secure and efficient data sharing and
analysis. In this paper, we review the research on combining blockchain and
machine learning technologies and demonstrate that they can collaborate
efficiently and effectively. In the end, we point out some future directions
and expect more researches on deeper integration of the two promising
technologies.
