The invention relates to a clamping device used for rock samples. The device includes a cylindrical cylinder body; an inner cavity used for accommodating a rock sample is constructed in the cylinder body; the device also includes axial clamping members which can be detachably installed on the cylinder body; the axial clamping members can be constructed to contact with the rock sample accommodatedin the inner cavity so as to clamp the rock sample; and the axial clamping members are provided with axial openings passing through the axial clamping members in an axial direction of the cylinder body, and/or the cylindrical cylinder body is provided with radial openings passing through the cylinder body in a radial direction of the cylinder body. The damages to the rock sample can be avoided byusing the device to clamp rocks.