In this paper we investigate the two-lane main road on-ramp system with signal-controlling using the cellular automata traffic flow model. The traffic signal is setup at the merging part between the main road and the on-ramp so that it can control the vehicles of both roads. We simulate the effect of traffic signal on vehicle flows of main road and on-ramp, and the traffic capacity and average velocity at the merging part are discussed. Through the analysis of the phase diagram, it can be found that the on-ramp system with two-lane main road can embody more complicated and realistic traffic flow characteristics than the on-ramp system with single-lane main road. Compared with the model introduced by Jiang Rui ［Jiang R 2003 J. Phys. A 36 11713］, the simulation results indicate that the state of traffic flow is improved obviously and the capacity of the on ramp system has increased.