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. European couplings are represented by Germany's KTR, Flender, Renold and Voith, following the DIN/ISO system. European products are mature in sealing, lubrication and anti-corrosion, with high modularity and integration. Compared with domestic GICL series, European designs excel at integrated coupling with gearboxes and brake discs, performing stably under continuous operation. Crowning of the tooth tip directly affects contact stress distribution. Domestic makers widely use CNC machining for tooth-form accuracy, while foreign makers have deeper know-how in optimizing the crowning curve and suppressing edge contact, helping reduce local stress concentration and abnormal noise. In summary, domestic crowned tooth couplings already have the technical basis to replace imports; users can select reasonably based on duty, budget and lead time. We will keep sharing selection and maintenance essentials for the GICL series.