In this paper, the characteristic impedance of transmission line and on-die termination (ODT) for Double Data Rate (DDR3) multi-module memory bus were be effectively enhanced signal integrity by particle swarm optimization (PSO) algorithm. The bionic characteristic of PSO has good performance of search for macrocosm and fast convergence. In this case, the equivalent model of the circuit considers that CPU/MCH and two dual in-line memory modules (DIMMs) connect by five segments of transmission lines. And the fitness function defined by the reflection coefficient for drive end is the small the better and the transmission coefficient for receiving end is the large the better. Finally, we verify enhancement of signal integrity for the DDR3 by simulating eye diagram.