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. In Japan, gear and crowned tooth couplings mostly follow standards such as JIS B 1452, with representative manufacturers including Sumitomo Heavy Industries and NTN. Their products emphasize modular design and high consistency, and are mature in precision transmission. Compared with domestic GICL series, Japanese products have richer experience in tooth crowning, noise control and batch stability, but purchase price and lead time are usually higher. 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.