In this study, WO3 and NiO thin films were deposited on the ITO/Glass substrates by radio frequency (RF) magnetron sputtering, respectively. The physical and electrochromic properties of thin films were investigated. On the other hand, the lithium perchlorate (LiClO4) powder was dispersed in propylene carbonate (PC) solvent to complete 1 M electrolyte. Then, as the 4.5 wt.% of ethyl cellulose and 8 wt.% ethylene carbonate (EC) were added to this electrolyte under stirring, a gel polymer electrolyte (GPE) was formed. Finally, the WO3 and NiO thin films obtained with the optimal deposition parameters were combined with the GPE to set up a complementary electrochromic device (CECD). The effects of the various coloring voltages on the electrochromic properties of CECD are investigated. The memory effect, energy-saving efficient, response time and switch lifetime of CECD are also estimated and discussed. Experimental results reveal that the amorphous thin films can be obtained with the RF power of 100 W and oxygen concentration of 60% at room temperature (RT). The thicknesses of WO3 and NiO films were approximately 530 nm and 180 nm, respectively. The stoichiometric of thin films were 2.99 for O/W ratio and 1.01 for O/Ni ratio. The GPE [(1 M LiClO4+PC)+ethyl cellulose(4.5 wt.%)+EC(8 wt.%)] exhibits a viscosity coefficient of 100 mPa∙s, a maximum ion conductivity (£m) of 7.17 mS/cm, a minimum activation energy (Ea) of 0.033 eV and a average visible transmittance of 82% at RT. The optimal electrochromic CECD (Glass/ITO/WO3/GPE/NiO/ITO/Glass) biased with a coloring/bleaching voltage of ¡Ó2.2 V revealed a transmittance variation (£GT%) of 54.53%, an optical density change (£GOD) of 0.790, an intercalation charge (Q) of 6.28 mC/cm2 and a coloration efficiency (£b) of 125.21 cm2/C at a wavelength (£f) of 550 nm. The chromaticity coordinates of CECD were x=0.289 and y=0.365 under the colored state. In addition, the energy-saving efficient of CECD was 15.19 W/V-m2 over the wavelength range between 380 nm and 780 nm. Also, it presented an open-circuit memory effect that the colored transmittance (£f at 550 nm) was 18.9% in 24 h. The total response time of the CECD was about 4 s for coloring and bleaching steps. After the repeated switch of 1,000 times, the £GT% of CECD was 43.57%. In this study, WO3 and NiO thin films with good adhesion, amorphous, and nearly stoichiometric were successfully deposited by RF sputter. Furthermore, high £m and high transmittance of GPE can be prepared easily and inexpensively. Our results demonstrated that the CECD exhibited the advantages of low applied voltage, high £b, fast response time and long-term memory characteristics.