Abstract: In this paper,a method for separating and determinating eight cephalosporins are developed with CS-930 Dual-Wavelenth Thin-Layer Chromatograph scanner. The cephalosporins are confirmed by their Rf and UV bsorbed curves,The relative recovery of extracting cephalothin from blood with chloroform is about 90%.The linear scope of quantiting cephalothin is between 0.5 and 8.0ug. The stability of cephalothin in postmortem blood is also investigated.