Abstract：The evolvement way of the plastic-loop closed by the deformation curve under the cycling loading and unloading conditions from the different displacement rates and the different load levels，and the different rock porosity(the compact fine-sandstone and the incompact aerated-concrete-brick) are introduced. The experimental results are analyzed，and the following phenomena are discovered：(1) rock deformation curve would form the plastic-loop under the cycling loading and unloading conditions because the deformation curve in loading zone differs from the deformation curve in unloading zone；(2) though the displacement change in the loading zone was more larger in the first circulate loading，the contrast of the displacement change in the loading zone of every cycling load would remain unchangeable since the second circulate loading，otherwise the contrast of the displacement change in the unloading zone would be un-conspicuous in the loading zone of every cycling load；(3) the slope of the load-displacement curve would increase when the displacement-rate increase，and the residual displacement after the first circulate loading and unloading would increase when the load-level increase；(4) in the load-displacement curve，the ending point of the unloading zone would be approximate the same as the starting point of the loading zone，i.e. new residual displacement from the second cycling load would not be generated；and (5) the response of the rock deformation to the different rock porosities under the cycling loading and unloading conditions would be different.
