Two-terminal electrical bistable device is fabricated with structure “Al/deoxyribonucleic acid-cetyltrimethylam- monium bromide/silver nanoparticles/deoxyribonucleic acid-cetyltrimethylammonium bromide/indium tin oxide”, and I-V curves are measured. The results show that the conductivity and the memristive characteristics are significantly improved by the embedding Ag nanoparticles layer. The optimal particle diameters are in a range of 15 - 20 nm, and the maximum on/off current ratio can reach 103. It is also found that I-V characteristic of the device depends on the sweeping voltage amplitude VA. As VA increases, switching voltages (VSET, VRESET) and the on/off current ratio ION/IOFF increase. Furthermore, the transition between high-and low-resistance-state depends on the direction of the applied electric field, which shows that the device possesses polarity.