Calix[n]Nd／MgBun2／HMPA is an effective catalytic system for the synthesis of the ultra-high molecular weight polystyrene (UHMWPS)．The catalytic activity of different Calix[n]Nd complex decreases in the following order：Calix[6]Nd＞Calix[4]Nd＞Calix[8]Nd．It shows that the aging of catalyst plays an important role on catalytic activity．The optimum conditions are as follow：Mg／Nd=20.0(molar ratio)

HMPA／Mg=1.0(molar ratio)

and aged 2.5 h under 50℃．The study of influence of solvent shows that toluene is a good solvent．The polymerization result shows that the conversion is over 80％ at 50℃

45 min．The kinetics of styrene polymerization using Calix[6]Nd-20MgBun2-20HMPA in toluene were investigated by weight method．It was found that the rate of polymerization is first order with respect to both monomer (St) and Calix [6] Nd concentrations．According to Arrhenius equation

it was found that polymerization activation energy is 41.7 kJ／mol．GPC characterization of obtained polymer shows：Mw=21.0×105

MWD=1.61．1H-NMR spectra of UHMWPS shows that the content of syndiotactic triad is 81％.