Electronic microprobe analysis (EMPA), X-ray diffraction (XRD), Raman spectrum, scan electronic microscope (SEM) and polarized optical microscope were used to study nephrite cat's eyes from Sichuan Province,Southwest China . The results indicate that the nephrite cat's eye mainly consists of aggregates of microcrystalline-cryptocrystalline tremolites. Fiber-shaped tremolites are parallel to each other in a certain direction. Fibroblastic texture is dominant, with which the nephrite can show good cat's eye effect, while tremolites with relatively thick fibers or bunchy and bundle fibers do not show satisfactory cat's eye effect. Fiber-shaped tremolites gear with each other tightly, which seems to be the major reason why the nephrite cat's eye displays high tenacity and break-resistant capability.