Nano water-based coatings for children's toys (wooden blocks/plastic dolls/metal toy cars/fabric toys) build a child-safe coating system in pure acrylic/water-based PU matrices via nano-SiO2 (particle size 10-20 nm, purely water-dispersed, zero VOC, zero formaldehyde, zero benzene series, food safety grade) + nano-ZnO (particle size 20-50 nm, antibacterial and antimold, >99% inhibition rate against bacteria and fungi on surfaces of toys mouthed by children, compliant with GB/T 21866) + nano-TiO2 (particle size 5-15 nm, photocatalytic decomposition of surface organic dirt, self-cleaning of saliva, milk stains and juice). EN 71-3:2019 (Toy Safety Part 3: Migration of Certain Elements, 19 heavy metals, extracted with simulated children's gastric fluid 0.07 mol/L HCl at 37°C for 2 h, tested by ICP-OES, migration of each element not exceeding respective limits: Sb<45, As<3.8, Ba<18750, Cd<1.3, Cr<37.5, Pb<2.0, Hg<7.5, Se<37.5 mg/kg). GB 6675.1-2023 (Toy Safety Basic Norms) and GB 6675.4-2023 (Migration of Certain Elements, aligned with EN 71-3). Saliva corrosion resistance — artificial saliva (ISO/TR 10271:2011): coating immersed for 72 h with no blistering, softening, discoloration or heavy metal migration, Delta E80%.