Aimed at the problems of strength’s slow development, slow setting and even super retarding happening at the top of cement slurry in deep and ultra-deep wells with long cementing intervals,a new type of polymer/inorganic composite retarder(PMC-180)was prepared by in-situ intercalated polymerization method.2-acrylamido-2-methylpropanesulfonic acid(AMPS),acrylic acid(AA),two diallyl dimethyl ammonium chloride(DMDAAC)were used as monomer,Modified montmorillonite was used as active polymerization filler,the structures and the thermal stability of PMC-180 were characterized by Fourier transform infrared spectroscopy(FT-IR),X-ray diffraction(XRD) and thermogravimetric analysis(TGA).Then, the application performance was evaluated and the retarding mechanism in cement slurry was discussed.The results show that the synthesized copolymer (PMC-180) is the target product with intercalation/exfoliation composite structure,The initial pyrolysis temperature of which reaches 267.27℃ and has good thermal stability.The cement slurry containing PMC-180 has good retarding property and salt/temperature resistance performance,the thickening time of the freshwater or brine cement slurry can be regulated effectively by adjusting the additives amount of PMC-180,moreover, the thickening curve of different kinds of cement paste is stable and no abnormal phenomenon such as bulging. The compressive strength of slurry containing PMC-180 is well developed at low temperature,which can be applied to long sealing and large temperature difference cementing and effectively alleviates super retarding phenomenon at the top of cement slurry.The slurry with PMC-180 which is easy to regulate and control has good compatibility with different cement slurry system and additives,and has good comprehensive performance.the retarding mechanismand temperature adaptation mechanismof PMC-180 were discussed by characterization methods of chemical analysis, X ray diffraction and scanning electron microscope:(1)PMC-180 is adsorbed on the surface of cement particles to formed a layer of hydration adsorption and the complexation reaction between PMC-180 and Ca2 is inhibiting the normal growth of Ca(OH)2 crystal nucleus or crystal, so the retarding effect is achieved finally;(2)the binding or release of effective retarding groups were controlled by the change of lamellar spacing being related to temperature in PMC-180,at the same time, the anions and cations in the molecular structure compete to adsorb each other on the surface of cement particles,therefore,The PMC-180 has good adaptability to large temperature difference,which mainly shows that it has a strong retarding effect at high temperature, and has a partial retarding effect at low temperature.