In this chapter, we distill the essence of security risk assessment within the industrial internet, focusing on the identification and quantification of potential threats. We explore the core principles and methodologies that underpin effective risk management, equipping readers with the knowledge to implement strategic protective measures. Through an in-depth case study on the intelligent manufacturing sector, we demonstrate the practical steps involved in assessing and mitigating security risks, emphasizing the importance of proactive measures to maintain the integrity and reliability of industrial systems. This chapter is designed to engage readers with a clear, concise overview of the critical role of risk assessment in today’s interconnected industrial landscape.