Abstract: The effect of guanidine hydrochloride (GuHCl) concentration on the oxidative refolding of denatured-reduced lysozyme of high concentration in the presence of artificial chaperone, that is, cetyl trimethyl ammonium bromide (CTAB) and β -cyclodextrin ( β -CD),was studied.A two-state refolding model was used to analyze the refolding kinetics.It was shown that there existed an optimum GuHCl concentration that gave maximum refolding yield of lysozyme.At this GuHCl concentration,the refolding rate constant increased, while the reverse refolding-rate constant decreased, with increasing artificial chaperone concentration,which led to the increase of refolding yield.The results indicated that the effect of artificial chaperone and GuHCl was cooperative in facilitating the refolding of denatured-reduced lysozyme.At the optimum GuHCl concentration,the spontaneous refolding yield of 1.05mg·ml ^-1 lysozyme in 60min was only 49%.In contrast, cooperated with artificial chaperone-facilitated refolding the recovery yield reached as high as 81%.