In piezoelectric energy harvesting (PEH), synchronous electric charge extraction (SECE) has the benefit of load independence. To reduce the energy dissipation on parasitic resistance, multi-shot SECE (MCE) was implemented to split the charge extraction process. In this paper, a multiple charge extraction with bias-flip (MCEBF) interface circuit is proposed. It not only reduces the dissipation in charge extraction but also enlarges the extractable energy of piezoelectric structure by adding a bias-flip action. MCEBF can also generate positive and negative voltage rails via buck-boost topology to supply power for double-rail devices. The analytical and experimental comparison among SECE, MCE, and MCEBF under different controls are also provided. In experiments, MCEBF offers a 57.3% improvement over SECE and 24% over MCE, in terms of harvested power.