Dielectric elastomer actuator (DEA) is considered as one of the most promising soft actuators due to its light weight, good flexibility, high actuated strain and energy density. Herein, a novel DEA material is developed by introducing a kind of SiO2 nanoparticles with strong interfacial polarizability into polydimethyl(methylvinyl) siloxane (PMVS). The 7.5 SiO2/PMVS DEA exhibits a high actuated strain of 31.3 % and blocked stress of 68.4 kPa, 2.4 and 2.9 times of pure PMVS DEA. A dual cone DEA (DCDEA) device was self-designed by using 7.5 SiO2/PMVS films, which possesses a high actuated displacement of 1.3 mm, output force of 0.3 N and energy density of 4.7 J/kg. More importantly, because of the high elasticity and strong interfacial interaction, the 7.5 SiO2/PMVS DCDEA exhibits a long fatigue life of 500,000 times, resulting in a full-life energy density of 2.3 × 106 J/kg, 39 times higher than that of the VHB based DCDEA.