The determination of reasonable pile spacing is one of the key technologies in anti-slide pole board wall design. The previous study on soil arch effect merely consider the action of long duration load instead of short-term load (seismic force). Based on the soil arch effect, this paper take account of side slope grade and the influence of seismic force, and analyze the strained condition of soil arch between piles. Through the controlling conditions by soil arch effect, the paper obtain a reasonable formula for calculating pile spacing.Combining with high intensity earthquake, this paper analyze the relation between pile spacing and landslide thrust behind piles,soil cohesion stress and internal frictional angle. Finally, it takes the anti-slide pole board wall project in Chongqing-Lichuan railway for example to analyze and validate , then come to the point that there is a difference between general design and seismic design of anti-slide pole board wall.