The development of room temperature NH3 sensors with flexible substrate can fulfill the future demands of high NH₃sensing performance under the premise of lower energy consumption and safety circumstance in wearable electronics field. The polyaniline and a serious of WO₃hollow spheres@ polyaniline hybrid were successfully synthesized via a combined route of simple hydrothermal method and in-situ chemical oxidative polymerization. The room temperature NH₃sensors were fabricated by assembling WO₃hollow spheres@ polyaniline hybrid on flexible polyethylene terephthalate (PET) films. The NH₃sensing properties of the fabricated devices demonstrated that the device utilizing 10 mol% WO₃hollow spheres@ polyaniline (PAWHs 10) hybrid exhibited the best sensing performance to 100 ppm NH₃(response value at 25) at 20℃. Moreover, the PAWHs10 hybrid sensor also achieved excellent NH₃selectivity, ppb-level detection limit (1.67-500 ppb NH3), and good response/recovery rates (136 s/130 s) at 20℃. The enhanced sensing performance of incorporation of polyaniline and WO₃hollow spheres was mainly attributed to the hollow structure of WO₃and the formation of p-n heterojunction between PANI and WO₃hollow spheres.