The crowned tooth gear coupling is a key component in modern heavy-duty shaft transmission; its crowned tooth meshing compensates angular, radial and axial misalignment between shafts. In China, the GICL, NGCL and GCLD series under GB/T standards are mainstream and widely used in metallurgy, mining and power industries. American gear couplings are based on AGMA standards; brands such as Falk, Lovejoy and Kop-Flex have deep influence in mining, energy and marine fields. AGMA products emphasize clear grading of rated torque and allowable speed, with structures biased toward durability and serviceability. Compared with domestic GICL, AGMA gear couplings offer richer choices in extra-high torque and special bore specifications. Selection should integrate operating torque, peak load, allowable speed and compensation capacity. The domestic GICL series covers nominal torque roughly Tn 630~450000 N·m, satisfying most medium-to-heavy scenarios; for extreme conditions (high temperature, strong corrosion, extra-long span), imported or custom solutions may be referenced. 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.