With the intrinsic characters of high voltage and low current, triboelectric nanogenerators (TENGs) serving as green high voltage (HV) power source exhibit excellent practicability and safety compared to traditional HV power sources. To further simplify the TENG-based HV power source system, a single electrode mode TENG (SE-TENG) with simple wiring is first employed to generate ultra-high voltage power in this work. By optimizing surface charge density and the thickness of packing layer between the primary electrode and reference electrode, a record value of 12.7 kV is achieved for SE-TENGs. Furthermore, a calculation method based on a capacitance model is proposed to accurately measure the open voltage of TENG with a wide range (over 10 kV). The SE-TENG-based HV power source is successfully applied to power electronics and generates negative air ions for air cleaning. This work significantly simplifies TENG-based HV power sources, and is expected to enrich the diversity of high-voltage applications based on the reach of existing technologies.