A leaky-wave antenna (LWA) supporting wide-band and continuous-beam scanning is proposed in this paper. It is based on a spoof surface plasmon polariton (SSPP) transmission line (TL) periodically loaded with circular patches. The optimized antenna structure enables its continuous-beam scanning of 69° from backward through broadside to forward with a stable high radiation gain as the operating frequency increases from 7 GHZ to 15 GHz (with a relative bandwidth of 72.73%). Furthermore, a perfect electronic conductor (PEC) reflector is added at a distance of about 0.3λ0 (λ0 is the vacuum wavelength for the broadside radiation) to improve the antenna gain, achieving a gain increase of about 3 dB. The proposed LWA is expected to find applications in planar wireless communication systems.