To get insight into the swelling and displacement law with seam dip angles change, similar simulation studies of gentle dip, dip and steep dip angles were conducted. The experiment angles and geometrical properties were chosen from a particular coal seam of various dip angles in Nantong Mining District. Digital speckle correlation method was used in the result analysis to quantitate the overburden strata deformation for the displacement and the total plane strain contour maps. Further analysis of the plane strain and displacement distribution gives the following major findings:generally the swelling and displacement condition will be relieved and the corresponding intense regions will rise to the upper boundary with the increase of seam angle; Based on the morphology in both contours, the interfaces of "Three Zones" were determined in the position of maximum value of contour, as well as height of caving zone and fractured zone and the eccentric degree in seam angle of gentle dip and dip; In the dip angle condition, stress arch-shell theory is used to determine height of fractured zone. Quantitative characteristic parameters show the distributions of caving zone and fractured zone are biased toward upper boundary while both heights exhibit a decrease trend.