The application of the fifth generation mobile communication networks (5G) and time sensitive networking (TSN) in the field of industrial automation has become a new trend,. As the new generation of mobile communication technology, 5G is featured with large bandwidth, low latency, ultra-reliable connection and multi-service slicing capacities; as the evolution goal of industrial ethernet, TSN is featured with deterministic transmission with bounded latency and jitter and guaranteed high reliability. Both technologies have been designed to provide converged communication for a wide range of services on a common network infrastructure. The coordination of 5G and TSN can effectively promote the integration of Information Technology (IT) and Operation Technology (OT), which will be an key enabler of Industrial Internet. Therefore, the collaborative transmission of 5G and TSN has become a focus for both industry and academia society. "5G+TSN" is envisioned to forge the general communication network for the future smart factory, which can enable the integration of various field level industrial communication technologies and ensure end-to-end industrial data transmission reliability. However, 5G and TSN networks are quite different with regard to transmission methods, protocols, control and management mechanisms, etc. How to realize the efficient inter-connection and coordination of 5G and TSN is a hot topic and difficult task currently. Following the general requirements of digital manufacturing, digital-networked manufacturing, and new-generation intelligent manufacturing, this article firstly introduces the state-of-the-art of time-sensitive networks, and it also elaborates on the standardization progress of 5G supporting TSN in 3GPP. Then, it emphasizes the main challenges for the coordinated transmission of 5G and TSN networks, and analyzes the key technologies such as time synchronization, connection enhancement, and unified resource management between the 5G and TSN heterogeneous networks. Finally, the application scenarios of the 5G-TSN coordination in the smart factory are given, which aims to deepen the integration of 5G into the industrial control and flourish 5G-based industrial applications.