A line-end cutting method for fin structures of FinFETs formed by double patterning technology firstly utilizes the SiN hard mask lines to form fin structures and then performs lithography and etching processes to form line-end cuts. Since the depth of the line-end cuts is large, there is enough time and space to regulate the etching recipe so as to balance the etching rate of multiple layers including the spin-on-carbon layer, the SiN layer, the SiO2 layer and the silicon substrate, thereby forming the fin structures with line-end cuts having flatter bottom topography, preventing the formation of silicon protrusions or silicon cones during the etching process and improving the device electrical performance.