Project Abstract Cancer mortality rate is very high. The biggest characteristic of cancer cells is rapid cell division, resulting in the hypoxia microenvironment of solid tumor. Our project is to construct three plasmids, which are transported to the solid tumor using the probiotics Nissle 1917 as gene delivery carrier. When the extracellular environment lacks of oxygen, a plasmid in Nissle 1917 can express invasin and Hyl proteins, making the Nisssle 1917 invade into tumor cells, and avoid cell lysosomes endocytosis. After the Nissle 1917 enter solid tumor cells, another plasmid will express Bmp2 protein, inducing cell apoptosis. The specialty of our project is that if the Nissle 1917 enter the nontumorous cells by mistake, the third plasmid will start suicide program, which will not pose a threat to normal cells, achieving the safety of gene therapy.