&NA;Arthroscopic knot tying is a crucial foundation in the field of arthroscopic surgery. The clinical outcome can be improved with solid understanding of its principle and proficiency on its technique. It is the obligation of surgeons to acquire the knowledge and skills before applying to their patients. The basic principles and techniques of arthroscopic knot tying are described in this article, including the practical way of classifying the knot configuration. The SMC knot deserves special attention in knot tying due to its internal locking mechanism, which has a crucial role in preventing the initial reverse slippage before the additional locking halfhitch throws.