Abstract: Xiaoaiping (XAP) isolated from the stems of marsdenia tenacissima, an asclepiadacease plant, has been documented to possess functions against inflammation and cancers. In this paper, we used the CCK-8 to measure the cell activity after XAP treatment according to the 1:1 of XAP and DMEM, and we found that XAP inhibited obviously the cell activity. We used confocal fluorescence microscope and fluorescence resonance energy transfer (FRET) to dynamic temporal-spatial distribution of SCAT3 and caspase-3 activation in single living human lung adenocarcinoma line (ASTC-a-1) cell expressing stably with the SCAT3. Experimental results showed that SCAT3 translocated from cytoplasm to nuclear, cell membrane and intracellular membrane area after 20min of XAP treatment, and the caspase-3 was activated rapidly about 100min of XAP treatment.