Cartilage angiogenesis inhibiting factor(CAIF)was purified from cartilage by guanidine hydrochloride extraction,acetone fractional precipitation, ultrafiltration,column chromatography.With SDS-PAGF,it showed a single band of CAIF with molecular weight of 27 700.By the methods of [ ³H]-TdR incorporation and the determination of mortality of cells,the effect of CAIF on the DNA synthesis and cytotoxicity of all cell lines were investigated and the inhibitory effect of CAIF on angiogenesis was measured by the experiment of chorioallantoic membrane of chicken embryos. The results showed that CAIF inhibited the endothelial cell strongly and Hela cell slightly;but not QGY7703 cell，human skin fibroblast，and mice myeloid cell. It also inhibited the angiogenesis in the chorioallantoic membrane of chicken embryos significantly. All these results suggest that CAIF has the inhibitory effect on angiogenesis. It is a specific angiogenesis inhibiting factor，and may be a useful drug on tumor therapy in some day.