Scattering characteristics and surface roughness on the surface of the materials make a very important influence on the performance of the product. The multi-wavelength fiber sensor for measuring surface roughness and surface scattering characteristics based on laser scattering was investigated. The special geometric design was used by the probe of fiber optic sensor, specimens with different surface roughness were analyzed by using 650 nm, 1 310 nm and 1 550 nm laser as the light source, respectively. The working distance of 2 mm was chosen as the optimum measurement distance. The experimental results indicate that under the same wavelength, the reflection intensity measured from the reflective surface of grinding samples decrease with the increase of surface roughness. Under the same roughness, the incident wavelength is longer, the reflection intensity is bigger. The multi-wavelength fiber sensor can accurately measure surface roughness, and can effectively reduce the system error. The range of relative error of fiber sensor by analyzing system error is about 3.56%-7.43%.