Abstract: Objective To study the tendency of amyloid precipitation of recom binant chicken cysteine proteinase inhibitory(chicken cystatin,cC)with natural N-terminal secreted by yeasts Pichia pastoris.Methods The recombinant cC was expressed in Pasteur yeasts(Pichia pastoris)bacterial strain X-33 with the inducement of the methyl alcohol.The cC could combine specifically with Cong ored.Thioflav in T fluorescence was used to detect accumulation characte ristics of cC.Results The quantity of amyloid cC accumulation increased significantly.Ultraviolate spectrophoto metric detection showed are cC content of 1.21 mol/L and fluorescent strength increased from 1.08 to 18.05 with an increased aggregation.Conclusion wild cystatin Calso has the tendency of amyloid precipitation.