Abstract: Industrial control system (ICS) is an important part of national infrastructure, widely used in energy, manufacturing, transportation, military and other industries, and is an important resource related to the national economy and people’s livelihood. Industrial control protocol is a crucial link for the ICS to achieve the organic linkage of many functions such as real-time data exchange, data acquisition, parameter configuration, status monitoring, abnormal behavior diagnosis, command issuance and execution, etc. Its security issues are closely related to the reliable and stable operations of ICS. In-depth security analysis of industrial control protocols is an important angle for understanding the security threats of ICS, and can provide guidance for the security protection of ICS. We investigate the security work of industrial control protocols from the academia and the industry, including research papers, standards and guidelines, attack incidents, etc. It systematically analyzes and summarizes the security problems faced by industrial control protocols. Firstly, we elaborate on the industrial control network architecture, the role and classification of industrial control protocols, and the comparison with traditional protocols. From the perspective of protocol design, implementation, and application, we conduct an in-depth analysis of industrial control protocol attack threats and security defense solutions. Finally, we discuss about the research trends on the security of industrial control protocols.