  In this paper, we systemically study the conformation characters of
rotational symmetric gel sheets with free boundary and investigate the role of
boundary on the equilibrium conformation. In gel sheet the boundary provides a
residual strain which leads to re-distribution of stress and impacts the shape
of equilibrium conformation accordingly. For sheet with boundary, the in-plane
stretching energy is far larger than the bending energy in some cases. It is
intrinsic different from closed membrane. In gel sheets, the boundary doesn't
only quantitatively amend to the elastic energy. The residual strain on
boundary cooperates with bending and stretching to determine the equilibrium
conformation rather than just the last two factors. Furthermore, on the
boundary of gel sheet, there is an additional energy induced by boundary line
tension $\gamma $. If $\gamma =0$, there is $10\%$ difference of elastic energy
from the experimental result. Finally, we discuss the effects of such line
tension $\gamma $ and propose a way to measure it by the border radius. It
redounds to study the physical origination of $\gamma $.
