Acrylate copolymers containing hydrophobic monomers (methyl methacrylate, butyl acrylate, styrene, or divinyl benzene) and hydrophilic monomer (acrylic acid) were synthesized by solution polymerization, and neutralized to form the soap-free hydrosol. The waterborne coating was prepared from the hydrosol crosslinked by M(NH3)(4)(2+) (M2+ was Zn2+, Cu2+, Ni2+ or Co2+). C-13-NMR analysis was used to identify the copolymer. The result of GPC showed that the molecular weight of the copolymer was within the range of thermosetting resin for coating. The factors affecting the crosslinking degree of the coating films were studied by DSC and gravimetric analysis. The results indicated that the appropriate crosslinking agent was Zn(NH3)(4)(2+), and the optimum curing condition was heating at 80 degrees C for 30 min.