Function, quality and cost are the three core elements of a product. Especially in the future, under the general trend of digitalisation and AI, it is a must for manufacturing companies to establish a complete cost engineering system. Based on 25 years of practical experience and method research in German and Chinese automotive companies, the author systematically introduces cost engineering system, cost engineering methods and their practical applications in the entire product process for the first time in this book, and presents a large number of practical examples of cost optimisation. Looking to the future, like the quality system standard, the cost engineering system also needs a standard for production companies. Cost analysis software, AI + cost engineering are important tools for manufacturing companies to fully and intelligently exploit the potential of cost optimisation.