Active constituents in Danshen and Compouud Danshen injections were determined by UV spectrometry and TLC scanning. Results showed that the total amount of catechol like constitucnts in injections obtaiued from thc market varies differeutly. It was proved that all the injectious containcd a large amount of tannius can lead to degeneration of red blood cells and agglutination of plasma protein and cause clinical toxic actions.