A conductive silver paste is prepared by mixing Ag Nanowires(AgNW) with different concentrations of Hydroxypropyl Methyl Cellulose (HPMC) in one-step process, and then a composite transparent electrode with Ag nanowires embedded in HPMC (AgNW:HPMC) is prepared by spin coating and subsequent hot pressing. The mass ratio of Ag nanowires and HPMC is changed by 1∶1, 1∶2 and 1∶3, and its effects on the photoelectric properties, roughness and stability of the transparent electrode were investigated. The results show that the conductive silver paste obtained by the one-step process can effectively prepare composite transparent electrodes with excellent performance. Increasing the ratio of HPMC in the conductive silver paste slightly decreases the conductivity and transparent of the AgNW:HPMC composite electrode due to the insulating and compactness properties of HPMC. While the flatness of the AgNW:HPMC composite electrodes is significantly improved with HPMC filling the empty space between the silver nanowires. The surface roughness decreases with increasing the proportion of HPMC, and the lowest Root-Mean-Square (RMS) roughness is only 4.6 nm when the mass ratio of Ag nanowires and HPMC is 1∶3. In addition, the composite electrodes with Ag nanowires embedded in HPMC exhibit remarkable stability under extreme conditions. When the nanowire electrode is exposed in atmosphere, HPMC can protect Ag nanowire from the corrosion of water and oxygen. The sheet resistance of the AgNW:HPMC electrode was doubled while the neat Ag nanowire electrode had lost its electrical conductivity after the electrodes were exposed in atmosphere for 21 days. Besides, HPMC can help the composite electrode maintain good photoelectric performance under the strong oxidative environment irradiated by ultraviolet light source. After 15 minutes of ultraviolet treatment, the sheet resistance only increased by 25%. Moreover, the adhesion properties of the AgNW:HPMC composite electrode is improved because HPMC strengthens the contact between the silver nanowires and the substrate, and the good photoelectric performance and surface morphology are still maintained under the destructive test with tape.