In heavy equipment, crowned tooth gear couplings are widely adopted for their high load capacity and strong misalignment compensation. After decades of technical accumulation, China has built a complete product system covering design, machining and inspection, gradually narrowing the gap with advanced foreign products. 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. 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.