With the upgrading of the equipment manufacturing industry, domestic requirements for crowned tooth couplings in accuracy, reliability and service life keep rising. Comparing Japanese, American and European counterparts helps clarify technical routes, standard differences and selection logic for equipment matching. Overall, Japan, the US and Europe each have their strengths in crowned tooth and gear couplings: Japan excels in tooth crowning and consistency, the US in high-torque grading and durability, and Europe in integrated design and sealing. The domestic GICL series, however, holds clear advantages in cost-performance, lead time and spare-part convenience, meeting most medium-to-heavy duty conditions. From a whole-life-cycle cost perspective, domestic crowned tooth couplings stand out in purchase price and spare-part supply, with convenient and short-cycle maintenance; imported products cost more upfront but offer better assurance for extreme conditions and long maintenance-free intervals, suiting critical host machines. Whether domestic or imported, correct installation, alignment and lubrication are prerequisites for coupling life. Mastering standard differences and structural features lets the crowned tooth coupling perform reliably in the transmission system.