Because of the simplicity of cells, the key to building biological computing systems may lie in constructing distributed systems based on cell–cell communication. Guided by a mathematical model, in this study we designed,simulated, and constructed a genetic double-branch structure in the bacterium Escherichia coli. This genetic double-branch structure is composed of a control cell and two reporter cells.The control cell can activate different reporter cells according to the input. Two quorum-sensing signal molecules, 3OC12-HSL and C4-HSL, form the wires between the control cell and the reporter cells. This study is a step toward scalable biological computation, and it may have many potential applications in biocomputing, biosensing, and biotherapy.