The　piezotronic　and　piezo-phototronic　effects　have　been　confirmed　as　promising　methodologies　to　optimize　the　performances　of　electronic/optoelectronic　devices.　Here,　the　carrier　concentration　dependence　of　both　the　piezotronic　and　piezo-phototronic　effects　are　systematically　investigated　in　ZnO　thin-film　transistors　(TFTs)　that　fabricated　by　high-concentration　solution　hydrothermal　method　(ZnO　NW　TFT)　and　radio　frequency　magnetron　sputtering　(ZnO　seed　TFT)　method.　Significant　performance　improvement　is　achieved　in　the　ZnO　NW　TFT　with　moderate　carrier　concentration　by　the　piezotronic　effect,　whereas　the　photoresponse　performance　of　the　ZnO　NW　TFT　to　365　nm　UV　illumination　shows　no　modulation　by　the　piezo-phototronic　effect.　In　contrast,　the　performance　of　the　ZnO　seed　TFT　with　ultra-low　carrier　concentration　almost　keeps　unchanged　when　introducing　the　piezotronic　effect,　while　significant　photoresponse　improvement　of　the　ZnO　seed　TFT　to　365　nm　UV　illumination　is　obtained　by　the　piezo-phototronic　effect.　After　careful　analysis　and　comparation,　the　different　influences　of　piezotronic　and　piezo-phototronic　effects　in　the　ZnO　NW　TFT　and　the　ZnO　seed　TFT　are　resulted　from　the　different　carrier　concentrations　in　ZnO　NW　film　and　ZnO　seed　film　with　or　without　UV　illumination.　This　study　not　only　presents　in-depth　understanding　about　carrier　concentration　dependence　of　the　piezotronic　and　piezo-phototronic　effects　in　ZnO　TFTs,　but　also　provides　feasible,　compatible　and　adjustable　methodologies　to　enhance/optimize　the　performances　of　electronic/optoelectronic　devices.