In this work，the stirring induced solution crystallization behaviour of cis-1，4-polybuta-diene polymerized with rare-earth catalyst (Ln-PB) has been studied by electron microscope，DSC and GPC．It has been found that when 0.5% Ln-PB toluene solution was stirred at a tern-perature within the range of -15°to -79℃ with a speed of 180 rpm，a kind of white swol-len thread-like substance wound around the sti stirer was formed． It was seen under electron microscope that this swollen thread-like substance consisted of fibrillar crystals of Ln-PB paral-lel to each other．The amount of Ln-PB wound around the stirrer increased with the decrease in crystallization temperature until a maximum was reached at about 一65℃．then it dec reased with the decrease in crystallization temperature．Howevcr，the higher the crystallization tem-perature，the higher the average molecular weight and the narrower the molecular weight distri-bution of Ln-PB which wound around the stirrer．Therefore，Ln-PB sample may be fraction-ated by stirring its dilute solution at a series of crystallization ternperatures．