Tri-silane coupling agent(TI-MPS) was synthesized with the yield of 94% by reacting 3- mercaptopropyltrimethoxysilane(MPS), triallyl isocyanurate(TI) and photoinitiator 2,2-dimethoxy-2-phenylacetophenone(DMPA) under 365nm UV-light. The structure of reaction product TI-MPS was confirmed by Fourier Transform Infrared Spectroscopy and 1HNMR spectrum. Properties of TI-MPS hydrolyzate after curing was studied. The results showed that the cured TI-MPS layer on iron sheet could withstand more than 100 cm?kg impact and bending level 1. The polarization resistance of the layer is 7459.3Ω?cm2. The performances of TI-MPS layer were superior to the single silane MPS layer. Salt spray accelerated corrosion tests showed the protective performance of TI-MPS is better than that of MPS. Especially the TI-MPS layer on aluminum sheet could resist 1000h salt spray test.