Surface plasmonics is the collective oscillation of the free electrons in the metal. Its unique properties render it highly valuable in a wide of interdisplinary areas, such as sensing, imaging, optoelectronics and nano-optics. I will introduce several new techniques to probe the optical properties of the surface plasmon. First, the distribution of the local field enhancement can be revealed by the ultrafast laser hole-burning method with surface-enhanced Raman scattering. It discloses some surprising fact of the surface plasmons. Second, the photoluminescence is observed by single particle spectroscopy and believed to originate directly from the radiative decay from the excited surface plasmon. Last, electron-phonon coupling rate in surface plasmon is determined by transient absorption.