The invention discloses an electronic ballast of a novel single-level circuit structure. The electronic ballast comprises a device for detecting voltage, current and phase of an input AC power supply;a rectifier bridge; a full-bridge inverter circuit; and an inverting control circuit; a serial resonance capacitor Cs and a serial resonance inductor L are further arranged at an output end of the full-bridge inverter circuit when the output end of the full-bridge inverter circuit is used as a gas discharge lamp of the load. By adding the serial resonance capacitor Cs and the serial resonance inductor L in the existing electronic ballast of the single-level circuit structure, the problem that the under-voltage causes the extinguishing of HID due to the zero-crossing point of the one-way sinewave DC can be effectively solved; due to the adding of a conduction angle on the whole one-way sine half-wave by the HID, a PF value is improved, and the harmonic wave is effectively reduced.