A method for determining the surface roughness parameters of metal film with surface plasmon spectroscopy is proposed. The angular distribution of scattering light intensity from two kinds of silver films, prism/silver film/air and prism/LB film/silver film/air was measured under the condition that surface plasmon was excited between the silver and air. By fitting the experiment data with calculating curves of theory, the characterization parameters for stochastic roughness interface were obtained.