This paper describes the development of ultra wideband and very low loss SAW filter based on the large electromechanical coupling coefficient Love wave mode, a Cu electrode/15°YX LiNbO3 structure was employed as a substrate. The design adopts the modified coupled mode model for accurate simulation and simulated annealing algorithm for the optimization of resonator parameters. The width/length weighted dummy electrodes were used to suppress spurious responses caused by the transverse mode resonances, and a viscous film was coated on the filter surface which is effective in suppress a spurious dip caused by Rayleigh mode. A filter with the center frequency of 620 MHz, -1 dB fractional bandwidth of 14.9%, -3 dB bandwidth of 18.3%, insertion loss of 0.94 dB, and out of band rejection of higher than 40 dB was fabricated.