In this paper, phosphate solid-state electrolytes with Li+ were prepared by the melt quenching method, and "ITO/TiO2:Nb/ZrO2″ and "ITO/NiO/ZrO2″ multilayers were fabricated on both sides of the electrolyte by sol-gel technology to construct "ITO/TiO2:Nb/ZrO2/phosphate electrolyte/ZrO2/NiO/ITO" all-solid-state electrochromic devices (ECDs). The optical and electrical properties of the electrolyte were investigated, and it was found that the material had a visible light transmittance of up to 89 % and a conductivity greater than 10−7 Scm−1 at temperature above 100 °C. Moreover, the ionic conductivity of the electrolyte gradually increased with increasing temperature. Simultaneously, the effect of the ZrO2 thickness on the device performance was investigated. The optical modulation amplitude (ΔT) and cycling number of the device initially increased and then decreased with increasing ZrO2 thickness. The optimal device was obtained with a 120 nm-thick ZrO2 layer, achieving a ΔT at λ = 630 nm of 48.39 %. Moreover, the ECDs in this paper demonstrated long-term optical memory; after 20 days of open-circuit memory measurement, there was only a 5.3 % increase in transmittance for devices in colored state.