The invention provides a deformation monitoring datum point device applicable to permafrost regions and a method for mounting the deformation monitoring datum point device. The device comprises a datum rod and a cylindrical sleeve. The datum rod is fixedly connected with a datum rod base, an inner hole is arranged at the bottom of the sleeve, the diameter of the inner hole is matched with that of the datum rod, and the diameter of the datum rod is smaller than the inner diameter of the sleeve. The method includes placing the datum rod in a drilled hole; filling clay mortar in the drilled hole until the depth of the filled clay mortar meets a certain requirement; sleeving the sleeve on the datum rod properly so that the top of the sleeve is lower than that of the datum rod; filling clay mortar in the drilled hole compactly; and filling lubricating materials which are not easy to freeze in cold seasons in a permafrost region between the datum rod and the sleeve so that mounting of the deformation monitoring datum point device is completed. The deformation monitoring datum point device and the method have the advantages that only the position of the sleeve can be changed in seasonal freezing and thawing processes, but the position of the datum rod used as a fixed point is not changed; interference to a datum point due to seasonal freezing and thawing effects of the permafrost region is effectively avoided, so that deformation monitoring accuracy is guaranteed; and the deformation monitoring datum point device is high in field mounting speed, simple and convenient to construct and high in reliability.