In view of the present steel structure the coating surface has long been eroded by sandstorm in the central and western region of Inner Mongolia. The sand flow injection test method was used to study the erosion wear on the steel structure coating in sandstorm. A formula for assessing the erosion degree of the coating was proposed. Through the similarity theory, the experimental results and the actual working condition were compared and analyzed. Results show that the erosion mass loss of the coating rises with the erosion speed; erosion mass loss is highest at 45° and lowest at 90°. The calculated results from the formula is in good agreement with the test results; the erosion results under the experimental condition of 360g/min, 30m/s and 12min are equivalent to those suffered erosion wear from 55 to 830 months in concentrated areas of actual sandstorm.