In order to meet the ESD protection requirements of small size devices, a STI double-fin structure with parasitic SCR based on fin technology is proposed. By adopting double-fin layout and deep doping technology, the base region width of the device was reduced, which avoided the SCR failure caused by weak conductivity modulation in fin technology. The simulation results show that compared with DFSD structure, the It2/Wlayout of the new structure is increased from 21.67 mA/μm to 28.33 mA/μm, and the trigger voltage Vt1 is decreased from 14.08 V to 9.64 V. The new structure can be turned on effectively and discharge large current under ESD stress.