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. Sealing and lubrication are critical to coupling life. Domestic GICL commonly uses lip seals with lithium grease—simple and easy to maintain; European products often adopt labyrinth seals with centralized lubrication interfaces, better suited to long-running, low-maintenance automated lines. Understanding the differences between domestic and foreign crowned tooth couplings helps make better decisions in equipment matching and retrofit. It is recommended to perform selection calculations for the specific duty and consult professional manufacturers when necessary.