The present work investigates the turbulence characteristics of a boundary layer flow over a two-dimensional step model with a rough surface. A hot wire Constant Temperature Anemometer (CTA) system with a split fiber probe and an X-type probe is used to investigate the turbulence characteristics in a wind tunnel experiments under neutral conditions. Two different types of windbreak fence are set on the step model surface. Porosities () of the fence are 0% and 50%. Measurements analysis includes mean velocity, turbulent velocity, Reynolds stress, turbulent energy and eddy viscosity profiles over the step model surface and in the wake region. The results obtained are as the following: a) Wind speed without fence is higher than that in the other cases adjacent to the solid surface, b) Flow separation is quite small at the windward corner of the step without fence and porous fence, and c) Distortion of flow at the windward corner of the step creates steep gradient of the velocity and large turbulent mixing.