The invention discloses a separator with a wide temperature range and a low heat shrinkage and a method for preparing the same. The invention belongs to the field of electrochemistry. The separator of the invention includes: an irradiation crosslinked fluoropolymer A with a melting point above 150° C. and/or a polymer B containing a benzene ring in its main chain; an ultrahigh molecular weight polyethylene having a molecular weight of 1.0×106-10.0×106, and a high density polyethylene having a density in the range of 0.940-0.976 g/cm3; the temperature difference between pore closing temperature and film breaking temperature of the separator is 80-90° C., preferably 85-90° C., the heat shrinkage of the separator is 2.0% or less. The separator of the invention has a high temperature difference between film breaking temperature and pore closing temperature, and a low heat shrinkage; when the separator of the invention is used in an electrochemical device, the reliability and safety of electrochemical device can be effectively improved.