High performance practical key terahertz applications.Highpowerterahertzoscillandatorscanberealizedradiationbyutilizsourceingisthethegreatimpedandevicecenforear π,2π and 3π stop-band which means that strong interaction can occur. Compared with the traditional Backward Wave Oscillator(BWO), the Band-edge Oscillator(BO) can achieve high power which can achieve the order of 100 W in W band and 1 W in the THz regime; can realize miniaturized device with Periodic Permanent Magnet(PPM) focusing system; can realize compact structure with Folded Waveguide Slow Wave Structure(FWG SWS) which is short in size and simple in structure; can realize low cost mass production. In this research, a stagger half-period FWG SWS and a novel operation concept for the BO with the folded waveguide are proposed. The BO is composed of Pierce-style double-anode convergent electron gun, periodic permanent magnet focusing system, diamond pill-box window and high efficiency collector. Several novel BOs above 100 GHz have been simulated, fabricated and tested, which achieved output power of 140 W at 100 GHz, 30 W at 120 GHz, and over 1 W at 300 GHz. The dispersion characteristics, design of devices and test results are described and analyzed.